Art as Argument #3: commutative diagrams in Category Theory

Following these posts on whether art could be understood as arguments, I turn attention to diagrams in pure mathematics.   I know of only two areas of mathematics where diagrams are used frequently as arguments in proofs, rather than simply as illustrations of arguments or proofs expressed in algebraic symbols. One area is Euclidean Geometry, which most of us learn in school. The other is category theory (CT). It is interesting that one of the oldest and one of the youngest branches of pure mathematics should be the only ones using diagrams in this way. Perhaps the rise of CT is another signal of the decline of the three-centuries-long dominance of the written word over western culture.
First, here is an example of a typical commutative diagram from category theory:
Commutative diagram square
This particular diagram expresses an equivalence:  that in traveling from P to S, it does not matter whether we travel via Q or we travel via R, the end-result will be the same.  (Category theory makes this notion of “same-ness” or equivalence quite precise; indeed, in some sense CT is a formal theory about different notions of equivalence and their relationship to one another.)  Thus, the diagram is making a claim about the (mathematical) world, a claim which may include its own proof:  that executing function (or action) w followed by function y is the same as executing function x followed by function z.
Let us see what CT textbooks say to justify the subject’s use of diagrams. The standard reference on CT for mathematicians is the book by Saunders Mac Lane. An easier introduction is the book by Lawvere and Schanuel. Both of these simply start using diagrams as proofs without any justification for the practice, although they both formally define the diagrams concerned. In the book by Barr & Wells, we find:

When the target graph of a diagram is the underlying graph of a category some new possibilities arise, in particular the concept of commutative diagram, which is the categorist’s way of expressing equations.” (page 93)

Later in the same chapter they say:

This point of view provides a pictorial proof that the composite of two graph homomorphisms is a graph homomorphism. . . . . . The verification process just described is called “chasing the diagram”. Of course, one can verify the required fact by writing the equations (4.14) and (4.15) down, but these equations hide the source and target information given in Diagram (4.13) and thus provide a possibility of writing an impossible composite down. For many people, Diagram (4.13) is much easier to remember than equations (4.14) and (4.15). However, diagrams are more than informal aids; they are formally-defined mathematical objects just like automata and categories. (page 96)

Mac Lane says (p. 29) that the use of arrows as a graphical representation of functions was introduced by Hurewicz in about 1940, and that he also probably first used commutative diagrams. Like many practices in mathematics, one learns about the use of diagrams as proofs in CT in the classroom. Despite the textual (ie, non-diagrammatic) nature of most pure mathematical writing, parts of applied mathematics and theoretical physics (e.g. Feynman diagrams) use diagrams although pure mathematicians may question whether these disciplines are actually doing “proving”.
References:
Michael Barr and Charkes Wells [1999]: Category Theory for Computing Science. Montreal: Les Publications CRM, 3rd edition.
W. Hurewicz [1941]: On duality theorems. Bulletin of the American Mathematics Society, 47: 562-563.
F. W. Lawvere and S. H. Schanuel [1997]: Conceptual Mathematics: A First Introduction to Categories. Cambridge: CUP.
Saunders Mac Lane [1998]: Categories for the Working Mathematician. Berlin: Springer, 2nd edition.

The French Member of the English Language Committee of the IMO

The International Mathematics Olympiad is a famous international competition for mathematics students. This is an excerpt from the diary of the Chairman of the English Language Committee (ELC) of the 2005 IMO , Geoff Smith:

In the evening I prepare for the English language committee which I will chair next day. This means I slope off to my room early and try to cast the questions in perfect English myself, in order to have something to start with.  The committee meets first thing in the morning. These days everyone is welcome in the ELC, including its most important member, the leader of France. We like to have simple sentences in IMO questions; ones which ideally can be translated almost word for word into as many languages as possible. French is rather special, and does not allow the rather free word order and grammatical latitude of English. Therefore the English language version has to be designed so that it can be easily translated into French. As each English sentence is suggested, we turn to FRA7, Claude Deschamps, to receive either a blessing (a shrug which indicates that all is well) or a sad shaking of the head which indicates that a particular piece of Anglo-Saxon thuggery simply cannot be expressed in French.”

HR runs amuck in NSW

The Sydney Morning Herald tomorrow reports that staff at the New South Wales Law Reform Commission are being invited to apply for their own positions.   Apparently, the current staff there are staying in their posts too long, thereby reducing staff turnover, with the serious consequence that: 

Zero turnover means that no opportunities arise to attract, develop or retain highly skilled employees.”  

It’s always the damn employees who cause trouble for the proper functioning of the Human Resources Department.   How can HR possibly execute policies to retain valuable staff if nobody ever threatens to leave!?

Obama the community organizer

Andrew Sullivan, in his British Sunday Times column yesterday, finally analyzes the MO of Barack Obama in terms of his background as a community organizer:

Obama is also, at his core, a community organiser. Community organisers do not jump into a situation and start bossing people around. They begin by listening, debating, cajoling, inspiring and delegating. Less deciders than ralliers, community organisers explain the options, inspire self-confidence and try to empower others, not themselves. If you think of Obama even on a global stage, this is his mojo. And those community organisers do not tell you to expect instant results. It takes time when you try to build real change from below. But the change is stronger, deeper and more real when it comes.

I guess I have to wonder what took you so long, Andrew?

Tony Benn in Rhodesia

Normblog today quotes an interview with former British Cabinet Minister and MP Tony Benn, talking about visiting Southern Rhodesia (now Zimbabwe) during WW II:
When I was there, there was no democracy at all: all the good land had been stolen and given to white farmers, no African had votes, it was a criminal offence for an African to have a skilled job; and now we lecture Zimbabwe on democracy – total hypocrisy.”
First, as so often with Benn, rhetorical effect takes priority over truth.   The franchise in Southern Rhodesia was not based on race, but on age, property ownership, income, and a test of English literacy.  Despite the inherent bias of these conditions (made worse by the use of a definition of “property” which excluded cattle, the main traditional form of black wealth), some black Rhodesians qualified to vote from the granting of self-government in 1923.  Of course, the number of black voters enrolled was tiny (in 1948, 248 non-whites to 48,000 whites enrolled), but even 248 is not zero.    Such a system allowed many white Rhodesians to convince themselves their electoral system was not racist.    The electoral situation in Rhodesia was undemocratic enough without Benn having to exaggerate it.
Second, the fact that any non-whites had the vote at all was due to British government insistence against the wishes of most of the Rhodesian white population, from 1898 onwards (see West 2002).  Benn’s statement jumps from a description of Southern Rhodesia in WW II straight to Zimbabwe in 2009, ignoring the campaigns for majority rule in the 1950s and 1960s, the international struggle and sanctions against the illegal UDI regime of Ian Smith, the British-sponsored negotiations leading to British-led peace-keeping forces, majority rule, and independence in Zimbabwe in 1980, and the political, technical, moral and financial support given by Britain for the newly-elected democratic Government of Robert Mugabe.   It is Mugabe and his ZANU-PF henchmen, not Britain, who have failed to honour the standards of democracy.   Like Norman Lamont in his deplorable support for the Chilean murderer Augusto Pinochet, Tony Benn seems to apply one standard to elections in Britain and another standard elsewhere.    As with Lamont, let me ask Benn:  Would it have been OK for John Major to have terrorized and murdered his opponents and refused to leave office when he lost the British election of 1997?  If not, then why is it OK for Robert Mugabe to do so?  Such a double standard strikes me as treating black people differently to white people.
 
POSTSCRIPT (2009-07-07):
The advisory Legislative Council established by the ruling British South Africa Company in Southern Rhodesia in 1898 had 6 appointed and 5 elected members, who were, from its creation, chosen under a non-racial franchise (see Walker 1953, p. 104).   This franchise was that in force in the Cape Colony, which itself dated from a Municipal Ordinance of 1836, which created a conditional, but colour-blind, franchise for some local governments based solely on ownership or rental of fixed residential property above stated monetary values.   Other tests, such as literacy in English, were added later to the conditions.  Indeed, the history of white rule in southern Africa in the 19th century can be seen as a fight between liberal, often colour-blind policies imposed from the Colonial Office in London but opposed by far-less-often liberal settlers, particularly those of Afrikaaner origin, who repeatedly left the area under British colonial jurisdiction to establish their own settlements further inland.
 
Reference:
Michael O. West [2002]:  The Rise of an African Middle Class:  Colonial Zimbabwe 1898 – 1965. Indiana University Press.
Eric A. Walker [1953]: The franchise in Southern Africa. Cambridge Historical Journal, 11 (1): 93-113.

Art as Argument #2

Following my earlier post about the possibility of a work of art being an argument, I want to give another example.  This example is also drawn from Australian aboriginal society, and involves a 1997 claim for legal title to land by the Ngurrara people over land in the Great Sandy Desert of Western Australia.  Frustrated by their inability to convince the Native Title Tribunal of their right to the land, the Ngurrara community decided to create a collaborative painting (photographed below) which would demonstrate their traditional rights. The painting was presented, and accepted, as evidence before the Tribunal and is therefore a work of argument, as well as a work of art.
Ngurrara II Canvas 1997
(The Ngurrara Canvas. Painted by Ngurrara artists and claimants, coordinated by Mangkaja Arts Resource Agency, May 1997. 10 metres x 8 metres. Photo: Mangkaja Arts Resource Agency.)
The case is mentioned in a 2003 New Yorker magazine article about aboriginal art by Geraldine Brooks, who says:

“In 1992, the Australian government first recognized the right of Aborigines to claim legal ownership of their ancestral lands – provided they could show evidence of having an enduring connection with them. Before proceeding to court, Aboriginal groups had to make their case before a Native Title Tribunal. Frustrated by their inability to articulate their arguments in courtroom English, the people of Fitzroy Crossing decided to paint their “evidence”. They would set down, on canvas, a document that would show how each person related to a particular area of the Great Sandy Desert – and to the long stories that had been passed down for generations.
“Ngurrara I”, the first attempt, was a canvas that measured sixteen feet by twenty-six feet and was worked on by nineteen artists. It was completed in 1996. But Skipper and Chuguna [two of the artists involved], in particular, didn’t feel that it properly reflected all the important places and stories, so more than forty additional artists were invited to produce a more definitive version. In 1997, “Ngurrara II”, which was twenty-six feet by thirty-two feet, was rolled out before a plenary session of the Native Title Tribunal. It was, one tribunal member said, the most eloquent and overwhelming evidence that had ever been produced there. The Aborigines could proceed to court.” (page 65).

 
References:
Geraldine Brooks [2003]: “The Painted Desert“, New Yorker, 28 July 2003, pp. 60-67.
Australian National Native Title Tribunal [2002]: Native Title Determination Summary – Marty and Ngurrara.  27 September 2002.  Background press release here.
Also, here is a transcript of a radio story (broadcast 1997-07-15) on Australian ABC radio about the submission of the painting as evidence to the Native Title Tribunal.
More on different forms of geographic knowledge here.

Step right up! Step right up!

Good morning and welcome to everyone who’s just arrived from Normblog!  Do come right in, and make yourself at home.  There are still seats up here near the front, and also over there by the poets.  (We apologize for the peanut shells some of the Beat poets left on the floor over there.)

Feel free to engage in an argument with us, especially regarding decision-theory or forecasting or even prophecy.  Although professionally we are interested in market planning and marketing strategy, we also have a special  interest in that hard-proving ground for data gathering, inference and complex reasoning, intelligence.  Indeed, some of our heroes worked in that arena, as well in politics and telecommunications and project management.  Eventually, though, even heroes become history.

What’s that? Oh, our tagline?  It’s from the opening of The Scalp Hunters: A Romance of Northern Mexico, by Captain Mayne Reid, published in 1860, and one of the young Teddy Roosevelt’s favourite books:

Unroll the world’s map, and look upon the great northern continent of America. Away to the wild west, away toward the setting sun, away beyond many a far meridian, let your eyes wander. Rest them where golden rivers rise among peaks that carry the eternal snow. Rest
them there.

So, browse around, stay as long as you wish, and do visit with us again when you have a free mo’.

Poem: Cat in Empty Aviary

Another poem from Aidan Coleman, whom I thank again for his permission to post this.

CAT IN EMPTY AVIARY
Today
is a day for weather:
sun-blue
with a scattering of popcorn.
Today
I’ll let the phone
ring
and only answer the kettle,
learn
idleness and bliss
from next-door’s lounging
cat
who dares a judgment
to come:
a prisoner
of nothing but sun.

cat in sun
References:
Aidan Coleman [2005]:  Avenues and Runways.  Australia: Brandl & Schlesinger Poetry.
Some more poems by Aidan Coleman can be found in an ABC Radio National podcast,  here.
Previous poetry posts can found be here.

Epistemic modal logic at the CIA

Jim Angleton
A recent issue of the TLS ran a review by Terence Hawkes of the biography by Michael Holzman of Jim Angleton, head of counter-intelligence at the CIA.  Holzman’s book, although mostly written from secondary sources, is a fine summary of Angleton’s life and career.  It is marred, however, by (a) Holzman’s annoying (academic) habit of quoting something or somebody and  then repeating, verbatim, key words from that very quotation in the following paragraph, as if we readers were idiots, unable to read for ourselves or contemplate an idea for longer than a paragraph.  And, (b) by a casual sloppiness about dates.  Call me old-fashioned, but I think a historian should not simply say “in  May that  year”  when the last mention of the specific year was some tens of pages and several anecdotes or set-pieces back.   No doubt Holzman always knows which of the 71 years of Angleton’s life and the various ones before or since he is currently referring to, but this is rarely obvious to the reader of this book, even to a careful reader.   In view of the subject matter and Holzman’s theme (that Angleton’s training in so-called practical criticism was invaluable to his career in counter-intelligence), one has to wonder if such sloppiness is deliberate.
Holzman also does not tell us much about the actual theory and practice of counter-intelligence, despite the title and the claims he makes up front.   In particular, his treatment of the Nosenko case is misleading, partly he believes the official CIA line and because he does not refer to the most recent publication on the case, namely the book by Bagley. Hawkes seems to have followed Holzman in his garden-path-up-straying.
Unlike literary criticism, espionage is not only about what to believe, it is also about what to do.  It may be the case that Yuri Nosenko was a genuine Soviet defector, as Holzman claims CIA eventually came to believe.  Others closely involved in the case, such as retired CIA agent Tennent Bagley (2007) have argued compellingly that Nosenko was in fact a KGB plant, not a genuine defector.
Whether or not Nosenko was a genuine defector, and whether or not CIA leadership believed him to be a genuine defector, CIA would also need to concern itself with what impact a revelation of their beliefs would have on KGB, as I have argued before, and thus on what proposition to seek to have KGB believe about CIA’s beliefs in the matter.   If CIA were seen by KGB to accept Nosenko’s testimony (inconsistent and incomplete, by his own admission) too quickly, KGB may not accept as genuine any CIA profession of belief in his bona fides.  So, some delay and equivocation in decision-making was called for.  If CIA professed to believe that Nosenko was a plant or allowed KGB to conclude that CIA believed Nosenko to be a plant, then CIA risked signalling to KGB that they (CIA) were also rejecting all the testimony he arrived in the west with, which included detailed protestations of KGB non-involvement in the assassination of President John F. Kennedy.    Whether or not CIA believed that KGB were involved in that assassination, they may or may not have wished to let KGB know what they believed, at least at that particular moment.  In any case, perhaps a clever (and cunning) CIA would seek to have KGB believe that Nosenko was believed, in order to see how the game played itself out.
So, one possible course of action for CIA was to signal to KGB that they accepted Nosenko as a genuine defector, but to signal also that they came to this decision only slowly and painfully.   How better to do this than to interrogate the man at length and (allegedly) harshly, and then, after years of apparent indecision and multiple internal investigations (some of which may even have been genuine), decide to accept him publicly as a true defector.   This public acceptance – consultancy fees, letters, flags, medals, and all – even now, four decades later, may have absolutely no connection whatever with what CIA leadership really believed then or, indeed, what they believe now.
It’s not only litcrit that gets an outing in these events.  If any philosopher reading this wonders about the practical usefulness of dynamic epistemic modal logic, wonder no more.
References:
Tennent H. Bagley [2007]:  Spy Wars.  New Haven, CT, USA:  Yale University Press.
Terence Hawkes [2009]: “William Empson’s Influence on the CIA.”  Times Literary Supplement, 2009-06-10.
Michael Holzman [2008]:  James Jesus Angleton, the CIA and the Craft of Counterintelligence.  Boston, MA, USA: University of Massachusetts Press.