As you can see, there’s a new site banner.
I got about a dozen submissions this time. They were all terrific, but something about this one just really grabbed me; it was absolutely exactly what I wanted. It was designed by Josh Gemmel. So Josh gets immortalized in the “about” tab of the blog.
Any of you folks who submitted a banner, if there’s some topic you want me to write about, drop me a note. I’ll try to do articles for all of you.
Thanks everyone for your time and effort!
Arrow Equality and Pullbacks
We’re almost at the end of this run of category definitions. We need to get to the point of talking about something called a *pullback*. A pullback is a way of describing a kind of equivalence of arrows, which gets used a lot in things like interesting natural transformations. But, before we get to pullbacks, it helps to understand the equalizer of a pair of morphisms, which is a weaker notion of arrow equivalence.
We’ll start with sets and functions again to get an intuition; and then we’ll work our way back to categories and categorical equalizers.
Suppose we have two functions mapping from members of set A to members of set B.
f, g : A → B
Suppose that they have a non-empty intersection: that is, that there is some set of values x ∈ A for which f(x) = g(x). The set of values C from A on which f and g return the same result (*agree*) is called the *equalizer* of f and g. Obviously, C is a subset of A.
Now, let’s look at the category theoretic version of that. We have *objects* A and B.
We have two arrows f, g : A → B. This is the category analogue of the setup of sets and functions from above. To get to the equalizer, we need to add an object C which is a *subobject* of A (which corresponds to the subset of A on which f and g agree in the set model).
The equalizer of A and B is the pair of the object C, and an arrow i : C → A. (That is, the object and arrow that define C as a subobject of A.) This object and arrow must satisfy the following conditions:
1. f º i = g º i
2. (∀ j : D → A) f º j = g º j ⇒ (∃ 1 k : D → C) i º k = j.
That second one is the mouthful. What it says is: if I have any arrow j from some other object D to A: if f and g agree on composition about j, then there can only be *one* *unique* arrow from C to D which composes with j to get to A. In other words, (C, i) is a *selector* for the arrows on which A and B agree; you can only compose an arrow to A in a way that will compose equivalently with f and g to B if you go through (C, i) Or in diagram form, k in the following diagram is necessarily unique:
There are a couple of interesting properties of equalizers that are worth mentioning. The morphism in an equalizer is a *always* monic arrow (monomorphism); and if it’s epic (an epimorphism), then it must also be iso (an isomorphism).
The pullback is very nearly the same construction as the equalizer we just looked at; except it’s abstracting one step further.
Suppose we have two arrows pointing to the same target, f : B → A and g : C → A. Then the pullback of of f and g is the triple of an object and two arrows (B×AC, p : B×AC → B, q : B×AC → C). The elements of this triple must meet the following requirements:
1. f º p = g º q
2. (f º p) : B×AC → A
3. For every triple (D, h : D → B , k : D → C), there is exactly one unique arrow A : D → B×AC where pºA = h, and q º A = k.
As happens so frequently in category theory, this is clearer using a diagram.
If you look at this, you should definitely be able to see how this corresponds to the categorical equalizer. If you’re careful and clever, you can also see the resemblance to categorical product (which is why we use the ×A syntax). It’s a general construction that says that f and g are equivalent with respect to the product-like object B×AC.
Here’s the neat thing. Work backwards through this abstraction process to figure out what this construction means if objects are sets and arrows are functions, and what’s the pullback of the sets A and B?
{ (x,y) ∈ A × B : f(x) = g(y) }
Right back where we started, almost. The pullback is an equalizer; working it back shows that.
Huh? How'd that happen?
As lots of folks around SB have been commenting today, Nature magazine has come up with a list of the top 50 science blogs, based on technorati ratings. According to them, GM/BM is the number 45 science blog in the world. Even if it is a screwy way of figuring out what science blogs are most widely read, it’s still just astounding that by any measure, this blog is ranked that high.
I’ve only been doing this blogging thing since March. And when I started, I really expected that I’d be lucky to get a dozen readers a day, if that. I thought I’d probably wind up giving up and folding within the first month.
Instead, it’s been four months, and there are somewhere around a thousand people reading this blog each weekday. (Or a hell of a lot more than that on a day like today, when I’ve been linked by DarkSyde on DailyKos and by the USAToday. Thanks to both of you!)
Thanks folks. I’m really amazed at how well this blog has been received; and I’m happier than I can really express to find out that people are interested in the crazy stuff I write about.
Also, while I’m chattering away: the GM/BM DonorsChoose challenge raised $1400 towards supporting math education. Those of you who donated, thank you! SB as a whole raised over $30,000 towards math and science education. That’s going to make a real difference to a lot of kids.
Peer Reviewed Bad ID Math
In comments to [my recent post about Gilder’s article][gilder], a couple of readers asked me to take a look at a [DI promoted][dipromote] paper by
Albert Voie, called [Biological function and the genetic code are interdependent][voie]. This paper was actually peer reviewed and accepted by a journal called “Chaos, Solitons, and Fractals”. I’m not familiar with the journal, but it is published by Elsevier, a respectable publisher.
Overall, it’s a rather dreadful paper. It’s one of those wretched attempts to take Gödel’s theorem and try to apply it to something other than formal axiomatic systems.
Let’s take a look at the abstract: it’s pretty representative of the style of the paper.
>Life never ceases to astonish scientists as its secrets are more and more
>revealed. In particular the origin of life remains a mystery. One wonders how
>the scientific community could unravel a one-time past-tense event with such
>low probability. This paper shows that there are logical reasons for this
>problem. Life expresses both function and sign systems. This parallels the
>logically necessary symbolic self-referring structure in self-reproducing
>systems. Due to the abstract realm of function and sign systems, life is not a
>subsystem of natural laws. This suggests that our reason is limited in respect
>to solve the problem of the origin of life and that we are left taking life as
>an axiom.
We get a good idea of what we’re in for with that second sentence: there’s no particular reason to throw in an assertion about the probability of life; but he’s signaling his intended audience by throwing in that old canard without any support.
The babble about “function” and “sign” systems is the real focus of the paper. He creates this distinction between a “function” system (which is a mechanism that performs some function), and a “sign” system (which is information describing a system), and then tries to use a Gödel-based argument to claim that life is a self-referencing system that produces the classic problematical statements of incompleteness.
Gödel formulas are subsystems of the mind
———————————————–
So. Let’s dive in a hit the meat of the paper. Section one is titled “Gödel formulas are subsystems of the mind”. The basic argument of the section is that the paradoxical statements that Gödel showed are unavoidable are strictly products of intelligence.
He starts off by providing a summary of the incompleteness theorem. He uses a quote from Wikipedia. The interesting thing is that he *misquotes* wikipedia; my guess is that it’s deliberate.
His quotation:
>In any consistent formalization of mathematics that is sufficiently strong to
>axiomatize the natural numbers — that is, sufficiently strong to define the
>operations that collectively define the natural numbers — one can construct a
>true (!) statement that can be neither proved nor disproved within that system
>itself.
In the [wikipedia article][wiki-incompleteness] that that comes from, where he places the “!”, there’s actually a footnote explaining that “true” in used in the disquotational sense, meaning (to quote the wikipedia article on disquotationalism): “that ‘truth’ is a mere word that is conventional to use in certain contexts of discourse but not a word that points to anything in reality”. (As an interesting sidenote, he provides a bibliographic citation for that quote that it comes from wikipedia; but he *doesn’t* identify the article that it came from. I had to go searching for those words.) Two paragraphs later, he includes another quotation of a summary of Godel, which ends midsentence with elipsis. I don’t have a copy of the quoted text, but let’s just say that I have my doubts about the honesty of the statement.
The reason that I believe this removal of the footnote is deliberate is because he immediately starts to build on the “truth” of the self-referential statement. For example, the very first statement after the misquote:
>Gödel’s statement says: “I am unprovable in this formal system.” This turns out
>to be a difficult statement for a formal system to deal with since whether the
>statement is true or not the formal system will end up contradicting itself.
>However, we then know something that the formal system doesn’t: that the
>statement is really true.
The catch of course is that the statement is *not* really true. Incompleteness statements are neither true *nor* false. They are paradoxical.
And now we start to get to his real point:
>What might confuse the readers are the words *”there are true mathematical
>statements”*. It sounds like they have some sort of pre-existence in a Platonic
>realm. A more down to earth formulation is that it is always possible to
>**construct** or **design** such statements.
See, he’s trying to use the fact that we can devise the Gödel type circular statements as an “out” to demand design. He wants to argue that *any* self-referential statement is in the family of things that fall under the rubric of incompleteness; and that incompleteness means that no mechanical system can *produce* a self-referential statement. So the only way to create these self-referencing statements is by the intervention of an intelligent mind. And finally, he asserts that a self-replicating *device* is the same as a self-referencing *statement*; and therefore a self-replicating device is impossible except as a product of an intelligent mind.
There are lots of problems with that notion. The two key ones:
1. There are plenty of self-referential statements that *don’t* trigger
incompleteness. For example, in set theory, I *can* talk about “the set of
all sets that contain themselves”. I can prove that there are two
sets that meet that description: one contains itself, the other doesn’t.
There’s no paradox there; there’s no incompleteness issue.
2. Unintelligent mechanical systems can produce self-referential statements
that do fall under incompleteness. It’s actually not difficult: it’s
a *mechanical* process to generate canonical incompleteness statements.
Computer programs and machines are subsystems of the mind
———————————————————-
So now we’re on to section two. Voie wants to get to the point of being able to
“prove” that life is a kind of a machine that has an incompleteness property.
He starts by saying a formal system is “abstract and non-physical”, and as such “is is really easy to see that they are subsystems of the human mind”, and “belong to another category of phenomena than subsystems of the laws of nature”.
One one level, it’s true; a formal system is an abstract set of rules, with no physical form. It does *not* follow that they are “subsystems of the human mind”. In fact, I’d argue that the statement “X is a subsystem of the human mind” is a totally meaningless statement. Given that we don’t understand quite what the mind is or how it works, what does it mean that something is a “subsystem” of it.
There’s a clear undercurrent here of mind/body dualism here; but he doesn’t bother to argue the point. He simply asserts its difference as an implicit part of his argument.
From this point, he starts to try to define “function” in an abstract sense. He quotes wikipedia again (he doesn’t have much of a taste for citations in the primary literature!), leading to the statement (his statement, not a wikipedia quotation):
>The non-physical part of a machine fit into the same category of phenomena as
>formal systems. This is also reflected by the fact that an algorithm and an
>analogue computer share the same function.
Quoting wikipedia again, he moves on to: “A machine, for example, cannot be explained in terms of physics and chemistry.” Yeah, that old thing again. I’m sure the folks at Intel will be absolutely *shocked* to discover that they can’t explain a computer in terms of physics and chemistry. This is just degenerating into silliness.
>As the logician can manipulate a formal system to create true statements that
>are not formally derivable from the system, the engineer can manipulate
>inanimate matter to create the structure of the machine, which harnesses the
>laws of physics and chemistry for the purposes the machine is designed to
>serve. The cause to a machine’s functionality is found in the mind of the
>engineer and nowhere else.
Again: dualism. According to Voie, the “purpose” or “function” of the machine is described as a formal system; the machine itself is a physical system; and those are *two distinctly different things*: one exists only in the mind of the creator; one exists in the physical world.
The interdependency of biological function and sign systems
————————————————————-
And now, section three.
He insists on the existence of a “sign system”. A sign system, as near as I can figure it out (he never defines it clearly) is a language for describing and/or building function systems. He asserts:
>Only an abstract sign based language can store the abstract information
>necessary to build functional biomolecules.
This is just a naked assertion, completely unsupported. Why does a biomolecule *require* an abstract sign-based language? Because he says so. That’s all.
Now, here’s where the train *really* goes off the tracks:
>An important implication of Gödel’s incompleteness theorem is that it is not
>possible to have a finite description with itself as the proper part. In other
>words, it is not possible to read yourself or process yourself as process. We
>will investigate how this parallels the necessary coexistence of biological
>function and biological information.
This is the real key point of this section; and it is total nonsense. Gödel’s theorem says no such thing. In fact, what it does is demonstrate exactly *how* you can represent a formal system with itself as a part, There’s no problem there at all.
What’s a universal turing machine? It’s a turing machine that takes a description of a turing machine as an input. And there *is* a universal turing machine implementation of a universal turing machine: a formal system which has itself as a part.
Life is not a subsystem of the laws of nature
———————————————-
It gets worse.
Now he’s going to try to put thing together: he’s claimed that a formal system can’t include itself; he’s argued that biomolecules are the result of a formal sign system; so now, he’s going to try to combine that to say that life is a self-referential thing that requires the kind of self-reference that can only be the product of an intelligent mind:
>Life is fundamentally dependent upon symbolic representation in order to
>realize biological function. A system based on autocatalysis, like the
>hypothesized RNA-world, can’t really express biological function since it is a
>pure dynamical process. Life is autonomous with something we could call
>”closure of operations” or a cluster of functional parts relating to a whole
>(see [15] for a wider discussion of these terms). Functional parts are only
>meaningful under a whole, in other words it is the whole that gives meaning to
>its parts. Further, in order to define a sign (which can be a symbol, an index,
>or an icon) a whole cluster of self-referring concepts seems to be presupposed,
>that is, the definition cannot be given on a priori grounds, without implicitly
>referring to this cluster of conceptual agents [16]. This recursive dependency
>really seals off the system from a deterministic bottom up causation. The top
>down causation constitutes an irreducible structure.
Got it? Life is dependent on symbolic representation. But biochemical processes can’t possibly express biological function, because biological function is dependent on symbolic representations, which are outside of the domain of physical processes. He asserts the symbolic nature of biochemicals; then he asserts that symbolic stuff is a distinct domain separate from the physical; and therefore physical stuff can’t represent it. Poof! An irreducible structure!
And now, the crowning stupidity, at least when it comes to the math:
>In algorithmic information theory there is another concept of irreducible
>structures. If some phenomena X (such as life) follows from laws there should
>be a compression algorithm H(X) with much less information content in bits than
>X [17].
Nonsense, bullshit, pure gibberish. There is absolutely no such statement anywhere in information theory. He tries to build up more argument based on this
statement: but of course, it makes no more sense than the statement it’s built on.
But you know where he’s going: it’s exactly what he’s been building all along. The idea is what I’ve been mocking all along: Life is a self-referential system with two parts: a symbolic one, and a functional one. A functional system cannot represent the symbolic part of the biological systems. A symbolic system can’t perform any function without an intelligence to realize it in a functional system. And the two can’t work together without being assembled by an intelligent mind, because when the two are combined, you have a self-referential
system, which is impossible.
Conclusion
————
So… To summarize the points of the argument:
1. Dualism: there is a distinction between the physical realm of objects and machines, and the idealogical realm of symbols and functions; if something exists in the symbolic realm, it can’t be represented in the physical realm except by the intervention of an intelligent mind.
2. Gödel’s theorem says that self-referential systems are impossible, except by intervention of an intelligent mind. (wrong)
3. Gödel’s theorem says that incompleteness statements are *true*.(wrong)
4. Biological systems are a combination of functional and symbol parts which form a self-referential system.
5. Therefore, biological systems can only exist as the result of the deliberate actions of an intelligent being.
This stinker actually got *peer-reviewed* and *accepted* by a journal. It just goes to show that peer review can *really* screw up badly at times. Given that the journal is apparently supposed to be about fractals and such that the reviewers likely weren’t particularly familiar with Gödel and information theory. Because anyone with a clue about either would have sent this to the trashbin where it belongs.
[wiki-incompleteness]: http://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorem
[gilder]: http://scienceblogs.com/goodmath/2006/07/the_bad_math_of_gilders_new_sc.php
[dipromote]: http://www.uncommondescent.com/index.php/archives/722
[voie]: http://home.online.no/~albvoie/index.cfm
The Bad Math of Gilder's New Screed
As several [other][panda] [folks][pz] have mentioned, George Gilder has written a [new anti-evolution article][gilder-article] which was published in the National Review.
[panda]: http://www.pandasthumb.org/archives/2006/07/the_technogeek.html
[pz]: http://scienceblogs.com/pharyngula/2006/07/if_it_werent_for_those_feminis.php
[gilder-article]: http://www.discovery.org/scripts/viewDB/index.php?command=view&id=3631
There’s a lot to hate in this article. It’s a poorly written screed, which manages to mix together all of Gilder’s bogeymen: feminists, liberals, anti-supply-siders, peer reviewers, academics, and whoever else dares to disagree with him about, well, anything.
Plenty of folks are writing about the problems in this article; as usual, I’m going to ignore most of it, and focus specifically on the mathematical parts of it. Given that his argument is mathematical at root, those errors are fatal to the argument of the article as a whole.
We start with a really strange characterization of Shannon information theory:
>After Wealth & Poverty, my work focused on the subject of human creativity as
>epitomized by science and technology and embodied in computers and
>communications. At the forefront of this field is a discipline called
>information theory. Largely invented in 1948 by Claude Shannon of MIT, it
>rigorously explained digital computation and transmission by zero-one, or
>off-on, codes called “bits.” Shannon defined information as unexpected bits, or
>”news,” and calculated its passage over a “channel” by elaborate logarithmic
>rules. That channel could be a wire or another other path across a distance of
>space, or it could be a transfer of information across a span of time, as in
>evolution.
What’s weird about this characterization is that there’s a very strange shift in it. He starts off OK: “the channel could be a wire or another path across a distance of space”. Where he gets strange is when he *drops the channel* as he transitions from talking about transmitting information across space to transmitting information across time. Space versus time is not something that we talk about in Shannon’s information theory. Information is something abstract; it can be transferred over a channel. What “transferred” means is that the information originated at entity A; and after communication, that information has been seen by entity B. Space, time – they don’t make a difference. Gilder doesn’t get that.
>Crucial in information theory was the separation of content from conduit —
>information from the vehicle that transports it. It takes a low-entropy
>(predictable) carrier to bear high-entropy (unpredictable) messages. A blank
>sheet of paper is a better vessel for a new message than one already covered
>with writing. In my book Telecosm (2000), I showed that the most predictable
>available information carriers were the regular waves of the electromagnetic
>spectrum and prophesied that all digital information would ultimately flow over
>it in some way. Whether across time (evolution) or across space
>(communication), information could not be borne by chemical processes alone,
>because these processes merged or blended the medium and the message, leaving
>the data illegible at the other end.
There’s a technical term for this kind of writing. We call it “bullshit”. He’s trying to handwave his way past the facts that disagree with him.
If you want to talk about information carried by a medium, that’s fine. But his arguments about “information can not be borne by chemical processes alone?” Gibberish.
DNA is a chemical that makes a rather nice communication channel. It’s got a common stable substrate on which you can superimpose any message you want – any information, any length. It’s an absolutely *wonderful* example of a medium for carrying information. But he can’t admit that; he can’t even really discuss it in detail, because it would blow his argument out of the water. Thus the handwaving “chemical processes can’t do it”, with absolutely no real argument for *why* a chemical process “merges the medium and the message”.
For another example of how this argument fails: consider a CD/RW drive in a computer. The medium is a piece of plastic with magnetic materials in it. The message is patterns of polarization of those materials. To “record” information on it, you heat it up, and you *modify the medium itself* by changing the polarization of the particles at a point.
Or best of all: take electromagnetic waves, his example of the “very best” communication medium. It’s a waveform, where we superimpose our signal on the wave – the wave isn’t like a piece of paper where we’ve stuck ink to its surface: we force it to carry information *by changing the wave itself*. The basic frequency of the wave, the carrier, is not modified, but the wave amplitudes *are* modified – it’s not just a simple wave anymore, we’ve combined the signal and the medium into something different.
What’s the difference between that and DNA? You can look at DNA as a long chain of sockets. Each socket must be filled with one of 4 different letters. When we “write” information onto DNA, we’re filling those sockets. We’ve changed the DNA by filling the sockets; but just like the case of radio waves, there’s a basic carrier (the underlying chain/carrier wave), and a signal coded onto it (the letters/wave amplitudes).
From this, he tries to go further, and start mixing in some computation theory, building on his lack of comprehension of information theory.
>I came to see that the computer offers an insuperable obstacle to Darwinian
>materialism. In a computer, as information theory shows, the content is
>manifestly independent of its material substrate. No possible knowledge of the
>computer’s materials can yield any information whatsoever about the actual
>content of its computations.
This is manifestly not true. In fact, there was a fascinating piece of work a few years ago where people were able to decode the cryptographic system used by a smartcard by using a combination of knowledge of its physical structure, and monitoring its power consumption. From these two things, they were able to backtrack to determine exactly what it was doing, and backtrack to stealing a supposedly inaccessible password.
>The failure of purely physical theories to describe or explain information
>reflects Shannon’s concept of entropy and his measure of “news.” Information is
>defined by its independence from physical determination: If it is determined,
>it is predictable and thus by definition not information. Yet Darwinian science
>seemed to be reducing all nature to material causes.
Again, gibberish, on many levels.
Shannon’s theory does *not* define information by its “independence from physical determination”. In fact, the best “information generators” that we know about are purely physical: radioactive decay and various quantum phenomena are the very best sources we’ve discovered so far for generating high-entropy information.
And even the most predictable, deterministic process produces information. It may be *a small amount* of information – deterministic processes are generally low-entropy wrt to information – but they do generate information.
And then, he proceeds to shoot himself in the foot. He’s insisted that chemical processes can’t be information carriers. But now he asserts that DNA is an information carrier in his sense:
>Biologists commonly blur the information into the slippery synecdoche of DNA, a
>material molecule, and imply that life is biochemistry rather than information
>processing. But even here, the deoxyribonucleic acid that bears the word is not
>itself the word. Like a sheet of paper or a computer memory chip, DNA bears
>messages but its chemistry is irrelevant to its content. The alphabet’s
>nucleotide “bases” form “words” without help from their bonds with the helical
>sugar-phosphate backbone that frames them. The genetic words are no more
>dictated by the chemistry of their frame than the words in Scrabble are
>determined by the chemistry of their wooden racks or by the force of gravity
>that holds them.
Yup, He says earlier “information could not be borne by chemical processes alone, because these processes merged or blended the medium and the message, leaving the data illegible at the other end.” And here he describes how DNA can carry information using nothing but a chemical process. Ooops.
And he keeps on babbling. Next he moves on to “irreducible complexity”, and even tries to use Chaitin as a support:
>Mathematician Gregory Chaitin, however, has shown that biology is irreducibly
>complex in a more fundamental way: Physical and chemical laws contain hugely
>less information than biological phenomena. Chaitin’s algorithmic information
>theory demonstrates not that particular biological devices are irreducibly
>complex but that all biology as a field is irreducibly complex. It is above
>physics and chemistry on the epistemological ladder and cannot be subsumed
>under chemical and physical rules. It harnesses chemistry and physics to its
>own purposes. As chemist Arthur Robinson, for 15 years a Linus Pauling
>collaborator, puts it: “Using physics and chemistry to model biology is like
>using lego blocks to model the World Trade Center.” The instrument is simply
>too crude.
This is, again, what’s technically known as “talking out your ass”. Chaitin’s theory demonstrates no such thing. Chaitin’s theory doesn’t even come close to discussing anything that could be interpreted as saying anything about biology or chemistry. Chaitin’s theory talks about two things: what computing devices are capable of doing; and what the fundamental limits of mathematical reasoning are.
One of the most amazing things about Chaitin’s theory is that it shows how *any* computing device – even something as simple as a [Turing machine][turing] can do all of the computations necessary to demonstrate the fundamental limits of any mathematical process. It doesn’t say “chemistry can’t explain biology”; in fact, it’s *can’t* say “chemistry can’t explain biology”.
[turing]: http://goodmath.blogspot.com/2006/03/playing-with-mathematical-machines.html
In fact, in this entire section, he never actually supports anything he says. It’s just empty babble. Biology is irreducibly complex. Berlinski is a genius who demonstrates IC in mathematics and biology. Chaitin supports the IC nature of biology. Blah, blah, blah. But in all of this, where he’s allegedly talking about how mathematical theories support his claim, he never actually *does any math*, or even talks about *how the theories he’s discussing applying to his subject*.
Site Banner
As you may have noticed, there’s a site banner up there now.
I only received one submission back when I requested people to submit banners. , and it just didn’t quite work for me. (Bit too dark, and I didn’t like the hint of a blurring effect on the letters.) Since no one else sent me anything, I finally broke down and threw something together myself. It’s OK, but I’m not wild about it. So I’m repeating my request:
Someone with artistic talent, *please* make me a banner. The requirements:
- The size should be roughly 760×90.
- Subdued colors; not glaringly bright. No hot pink. I tend to like blues and violets, but I’ll be happy with anything that doesn’t hurt my eyed.
- Easy to read text, including the name of the blog, and the subtitle that are currently there. I’d rather not have funny fonts mixed into the title.
- Something in the background that suggests the kind of math I do. Since my approach to math is much more focused on discrete math topics like structures and logic, I’d prefer to see something like graphs, category diagrams, topologies, or knots than equations.
The rewards for the person whose banner I use:
- You’ll be eternally credited in the “about” link on the blog.
- You can pick a topic for me to write a blog entry or series of entries about.
- If I ever collect the blog entries into a book, you’ll get a free signed copy.
Categories and SubThings
What’s a subset? That’s easy: if we have two sets A and B, A is a subset of B if every member of A is also a member of B.
What’s a subgroup? If we have two groups A and B, and the values in group A are a subset of the values in group B, then A is a subgroup of B.
For any kind of thing **X**, what does it mean to be a sub-X? Category theory gives us a way of answering that in a generic way. It’s a bit hard to grasp at first, so let’s start by looking at the basic construction in terms of sets and subsets.
The most generic way of defining subsets is using functions. Suppose we have a set, A. How can we define all of the subsets of A, *in terms of functions*?
We can take the set of all *injective* functions to A (an injective function from X to Y is a function that maps each member of X to a unique member of Y). Let’s call that set of injective functions **Inj**(A). Now, we can define equivalence classes over **Inj**(A), where two functions f : X → A and g : Y → A are equivalent if there is an isomorphism between X and Y.
The domain of each function in one of the equivalence classes in **Inj**(A) is a function isomorphic to a subset of A. So each equivalence class of injective functions defines a subset of A.
We can generalize that function-based definition to categories, so that it can define a sub-object of any kind of object that can be represented in a category.
Before we jump in, let me review one important definition from before; the monomorphism, or monic arrow.
>A *monic arrow* is an arrow f : a → b such that (∀ g1,
>g2: x → a) f º g1 = f º g2
>⇒ g1 = g2. (That is, if any two arrows composed with
>f in f º g end up at the same object only if they are the same.)
The monic arrow is the category theoretic version of an injective function.
Suppose we have a category C, and an object a ∈ Obj(C).
If there are are two monic arrows f : x → a and g : y → a, and
there is an arrow h such that g º h = f, then we say f ≤ g (read “f factors through g”). Now, we can take that “≤” relation, and use it to define an equivalence class of morphisms using f ≡ g ⇔ f ≤ g &land; g ≤ f.
What we wind up with using that equivalence relation is a set of equivalence classes of monomorphisms pointing at A. Each of those equivalence classes of morphisms defines a subobject of A. (Within the equivalence classes are objects which have isomorphisms, so the sources of those arrows are equivalent with respect to this relation.) A subobject of A is the sources of an arrow in one of those equivalence classes.
Bible Code Bozos
Earlier this week, I posted [a brief article][nyc-boom] about the [“True Bible Code”][tbc] folks who claimed that NYC was going to be hit by a terrorist nuclear weapon this weekend.
I was looking at the rest of their site to see what their “true bible code” was. I was expecting something along the lines of the gap codes or yet another low-budget gematria. It turns out to be much more humorous than either of those.
Most of the bible-code type nonsense you find is based on simple rules. There’s a good reason for that: the more complex the rules get, the more likely they are to be artifacts. The more elaborate the rule, the less convincing it’s going to be as a real code, and the more likely it is to be an artifact of the natural structure of the language combined with that human pattern-finding ability.
The gap-coding is a good example of what a hidden-code system might really look like. It’s not obvious; but it’s simple enough to be able to look for the patterns. If it had turned out that the bible really had patterns coded that way, but you couldn’t find similar patterns in other texts, that would have been interesting. (In the original publication, they claimed only the old testament contained those patterns; but numerous folks [have shown that claim to be false][bc-debunk]. It’s an artifact of the natural structure of the hebrew language.)
In contrast – the more complex a system of rules gets, the more it includes special cases, conditions, alternatives, and subjective choices, the less likely it is to have any possibility of representing anything real. Language is complicated enough that if you take any text, and start adding rules, you can develop a system of rules which will describe properties of that text.
It’s a lot like working with machine learning algorithms. A machine learning algorithm is trained by taking a sequence of stuff as input (called training data), and analyzing it. The idea is that you feed it a bunch of data that has some property that you’re interested in; and after it’s been trained, it will be able to recognize other things with that property. Some machine learning algorithms [like decision trees][decision-tree] actually generate human-readable rules to describe the procedure it’s going to follow. One other thing that these kinds of algorithms can often do is provide an *exemplar*: a datum that is a typical example of a datum that matches a rule.
When you use machine learning on a set of data, and you set the parameters to make it very sensitive, very precisely selecting properties of the input data, you tend to get very strange, elaborate rules. For example, on the linked wiki page, they show a decision tree for helping you determine whether or not you should play golf on a particular day. Some of the rules are things like “If it’s sunny and the humidity is less than 70%, then you should play”. If the parameters were set to be too sensitive, you might end up with a rule like “If it’s sunny, and the humidity is greater than 12% and less than 42%, or greater than 51% but less than 68%, and it’s a tuesday or friday before 12pm in the summer, or it’s a wednesday after 4pm in the autumn, and at least one person you’re going to play with has a name that starts with ‘J’ or ‘P’, then you should play.”
The point of this little aside is that if you’re determined to find a set of rules that specifically describes one particular set of data, you can. But it’s going to be a very bizzare set of rules that really makes no sense.
So… Back to these “True Bible Code” guys. They’ve got incredibly elaborate rules. Twenty of them. Each of which has multiple cases and conditions. Let me give an example – what they call [the symbolic structure principle][tbc-symbolic] – which is one of their initial rules, and *not* one of the most complicated.
>Every literal account in the bible has the normal literal meaning.
>
>Every non literal account, such as a dream, a parable or a vision, has a
>straightforward symbolic meaning, which is the symbolic meaning of the
>events described in the account. We call this the Event Symbolic meaning, or
>the Event Symbolism.
>Every interpretational sub account in the bible has its normal literal
>meaning which describes the event symbolic meaning of one or more symbolic
>sub accounts. If the interpretation has symbolic sections then these have
>event symbolic meanings.
>
>Every account in the bible, which:
>
>[1] contains a ‘countable noun’, which is a noun acting as a noun (or a
>participle which declines as a noun which is used as a noun, such as a
>’baker’ – the one causing [things] to be baked – a Hiphil participle in
>Hebrew) which is repeated an even number of times (wherein all repeated
>words take the same meaning in the literal account or in the event
>symbolism), and which does not contain a double designation – see [Code6b]
>or which
>
>[2] has a parallel account elsewhere in the bible,
>
>has a further set of one, two, three or four (so far as we have found) word
>symbolic meanings.
>
>The number of Word Symbolic meanings in a sub account is determined by the
>Successive Designations Principle below – see [Code6b]. These greater
>meanings are in addition to the literal meaning, in the case of a literal
>account, and are in addition to the straightforward symbolic meaning, the
>event symbolic meaning, in the case of a symbolic account such as a dream, a
>vision or a parable. They are in addition to the literal/event symbolic
>meaning of an interpretational sub account.
>
>If a bible account contains an interpretational subaccount (typically an
>interpretation from Jesus, Daniel or Joseph), then the literal meaning of
>the interpretation is the event symbolic meaning of the symbolic subaccount
>which it is interpreting. Obviously since the narrative is also literal, its
>literal meaning sets the scene for the event symbolic meaning of all of its
>symbolic subaccounts.
>
>The first word symbolic meaning of any interpretational subaccount is the
>first word symbolic meaning of the symbolic subaccount which it interprets.
>Furthermore the existence of a first word symbolic thread in an
>interpretational subaccount unites the first word symbolic meaning of the
>narrative to the first word symbolic meaning of the symbolic subaccount
>which the interpretation is explaining.
>
>Likewise the second, third, fourth word symbolic meanings of any
>interpretational subaccount (if they exist) are the second third fourth word
>symbolic meanings of the symbolic subaccount which it interprets.
>Furthermore the existence of a second, third, fourth word symbolic thread in
>an interpretational subaccount unites the second, third, fourth word
>symbolic meaning of the narrative to the second, third, fourth word symbolic
>meaning of the symbolic subaccount which the interpretation is explaining.
>
>Likewise the non existence of a first second third fourth word symbolic
>thread in an interpretational subaccount decouples the first second third
>fourth word symbolic meaning of the symbolic account which it interprets
>from the first second third fourth word symbolic meanings of the narrative
>respectively.
After that whopper of a rule, they go through six examples; followed by four “proofs”. The proofs are pretty much indistinguishable from the examples. For example, here’s the shortest one, the fourth “proof”.
>Finally we have the shortest parable in the bible which is:
>
>33 Another illustration he spoke to them: The kingdom of the heavens is like
>leaven, which a woman took and hid in three large measures of flour, until
>the whole mass was fermented/leavened (Matthew 13).
>
>Ok, you young paduan learners! If it is the most insignificant and smallest
>of the parables in the whole bible, then what does this tell you about its
>spiritual meaning in this upside down world in which we live?
>
>Yes, it is the greatest of them all in meaning. Well, the event symbolic
>meaning is as follows:
>
>The woman is the holy spirit, the leaven is the bible code, and the three
>lumps of flour are the literal, the event symbolic and the account symbolic
>meanings of the bible. When the whole mass is fermented/leavened (decoded),
>then we can truly eat the whole book and see both the code and the truth and
>God and the true religion and his plan and his love and his humour and his
>righteousness, and our total and utter pretentiousness and stupidity
>stretching over 3500 years. As regards the account symbolic meaning of
>Matthew 13:33 and the parallel account in Luke 13:20 please see section[69].
>
>This leaven is not the wicked teachings of the Pharisees but is rather the
>good teachings of the true priesthood of God. This website is the result of
>such leaven. We are expanding the bread of heaven to make it fully
>digestible.
This looks a *lot* like what I would expect as the output from a rule-generating machine learning system – right down to that so-called “proof”, which isn’t a proof, but an examplar. As a computer scientist, if I saw my system generating a rule like this, my reaction would be to adjust the parameters – because I’m clearly generating garbage. For *any* large set of documents, you *can* come up with a set of rules that matches them. The question is, do they matter? Do they have any real meaning, or are they just coincidental? The answer is usually that elaborate multicondition rules, particularly when they involve subjective terms, is that they’re meaningless coincidence. Like the ones here.
[nyc-boom]: http://scienceblogs.com/goodmath/2006/06/good_math_bad_math_might_be_in.php
[tbc]: http://www.truebiblecode.com/
[tbc-symbolic]: http://www.truebiblecode.com/code.html#c5
[bc-debunk]: http://www.postfun.com/pfp/bible/code.html
[decision-tree]: http://en.wikipedia.org/wiki/Decision_tree
Friday Random Ten, June 30
It’s that time of the week again, when I bore you with my bizzare taste in music. Quite an eclectic mix this week.
- Spock’s Beard, “Thoughts”. A track from an oldish Spock’s Beard album. SB is an American neoprog band, which sounds something like a blend of old Genesis, Kansas, and Rush. Very good band. This isn’t my favorite of their albums (that would be “V”).
- Gentle Giant, “Way of Life”. A classic song off of a classic album.
- Whirligig, “Mister Fox”. An interesting little ballad by a wonderful NYC based Irish band.
- Peter Gabriel, “San Jacinto”. Peter Gabriel at his absolute best. He’s never done anything to match the “Security” album, and this is one of my favorite tracks off of there. Starts off mellow and kind of mysterious sounding, and gradually builds, and then fades.
- The Clogs, “Lady Go”. A track with vocals from one of those “post-rock ensembles” that I love so much. Very strange sounding; partly a capella falsetto; lots of dark rythmic stiff in other parts.
- Broadside Electric, “Tam Lin”. The old traditional ballad performed by a really cool local electric folk band. (And one of the members of the band is actually a math professor at Suny Stonybrook! But she hadn’t joined yet on this album.)
- Mel Brooks & broadway cast of “The Producers”, “Springtime for Hitler”. The original producers is one of my all-time favorite comedy movies. I still haven’t managed to get in to see the show. But the soundtrack is absolutely brilliant.
- Psychograss, “Looks like a Duck”. Psychograss is a thoroughly amazing band: Tony Trischka, David Grier, Mike Marshall, Darol Anger, and Todd Phillips. They’re mostly bluegrass, but with various strange influences mixed in. This track has some of the most subtly amazing banjo playing you’ll ever hear, not to mention a knockout fiddle bit at the end.
- John Corigliano (performed by Stanley Drucker), “Clarinet Concerto, movement ii: Antiphonal Toccata”. I’m actually a classically trained clarinetist. I used to think that I didn’t like Stan Drucker’s playing. Then I heard this. I’ve since learned that while his performances of some of the old classical standards for Clarinet (Mozart’s Clarinet Concerto, the Weber concertos, etc.) are rather uninspired, he is utterly magnificent when it comes to modern music. He clearly loves playing the newer stuff, and it shows. This is also the most technically challenging piece for Clarinet that I’ve ever heard.
- Vasen, “Sluken”. Vasen is a Swedish folk band. The lead player plays a peculiar instrument called the Nyckelharpa – it’s a violin with a keyboard. They’re a great band, especially if you get to see them live.
One more plug for DonorsChoose
This is the last time I’m going to bug folks to remind them to donate to the SB challenges.
The DonorsChoose fundraiser here at ScienceBlogs is just about over. Three more days for you to help some kids get a good education in math and science. The GoodMath/BadMath challenge is here; and Janet has a rundown on the challenges that are close to their goals. (If the challenge is met, DonorsChoose will add in an extra 5% bonus.)
As an extra incentive, for the next 10 people who donate to the GM/BM challenge, if you send me a copy of your DonorsChoose receipt, I’ll let you pick one topic for me to write a post about. The only restriction is that the topic be related to some kind of math – good or bad – and that it’s legit. (So don’t send me some good math and ask me to write a bad math post about it.)
Please, do go over to DC, and donate whatever you can afford, As I said at the very beginning of our drive, I’ve taught kids from the kinds of schools that we’re trying to help. There’s something deeply wrong with a school where you have kids who want to learn, but they don’t really get the chance, because they don’t have the things they need – like textbooks.