Thursday, December 17, 2009

Worst Commutative Diagram Ever

Okay, mathematical hotshots! This commutative diagram appears in a legitimate math book, despite its appearance. What fact is it proving? Leave your answers in the comments. Second-year UW math students may not respond.

Revision: nobody who was in spring quarter of last year's algebra class can answer. Other second year math students, feel free.


JBL said...

An officemate of mine immediately identified this as coming from Eisenbud's book, and shortly thereafter was able to find the actual page from which it came. (He asserts that he recognized not the diagram itself, but the font it was written in.) Combinatorialist that I am, my main objection is that the graph associated to this diagram appears to be planar, so can be displayed without five (!) crossings (and probably can be displayed nicely using straight lines and at most one crossing).



Anonymous said...

Here's my vote: