
Penrose tilings and noncommutative geometry
Penrose tilings are aperiodic tilings of the plane, made from 2 sort of tiles : kites and darts. It is well known (see for example the standard textbook tilings and patterns section 10.5) that one can describe a Penrose tiling around a given point in the plane as an infinite sequence of 0’s and 1’s, […]

changes (ahead)
In view or recents events & comments, some changes have been made or will be made shortly : categories : Sanitized the plethora of wordpresscategories to which posts belong. At the moment there are just 5 categories : ‘stories’ and ‘web’ (for all posts with low mathcontent) and three categories ‘level1’, ‘level2’ and ‘level3’, loosely…

Langlands versus Connes
This is a belated response to a MathOverflow exchange between Thomas Riepe and Chandan Singh Dalawat asking for a possible connection between Connes’ noncommutative geometry approach to the Riemann hypothesis and the Langlands program. Here’s the punchline : a large chunk of the ConnesMarcolli book Noncommutative Geometry, Quantum Fields and Motives can be read as…

Views of noncommutative spaces
The general public expects pictures from geometers, even from noncommutative geometers. Hence, it is important for researchers in this topic to make an attempt to convey the mental picture they have of their favourite noncommutative space, … somehow. Two examples : This picture was created by Shahn Majid. It appears on his visions of noncommutative…

the ManinMarcolli cave
Yesterday, Yuri Manin and Matilde Marcolli arXived their paper Modular shadows and the LevyMellin infinityadic transform which is a followup of their previous paper Continued fractions, modular symbols, and noncommutative geometry. They motivate the title of the recent paper by : In [MaMar2](http://www.arxiv.org/abs/hepth/0201036), these and similar results were put in connection with the so called…

2006 paper nominees
Here are my nominees for the 2006 paper of the year award in mathematics & mathematical physics : in math.RA : math.RA/0606241 : Notes on Ainfinity algebras, Ainfinity categories and noncommutative geometry. I by Maxim Kontsevich and Yan Soibelman. Here is the abstract : We develop geometric approach to Ainfinity algebras and Ainfinity categories based…

coalgebras and nongeometry 2
Last time we have seen that the _coalgebra of distributions_ of an affine smooth variety is the direct sum (over all points) of the dual to the etale local algebras which are all of the form $\mathbb{C}[[ x_1,\ldots,x_d ]] $ where $d $ is the dimension of the variety. Generalizing this to _noncommutative_ manifolds, the…