## Cohomology for computer science

Alex Lubotzky

Hebrew University of Jerusalem

November 17, 2015

We will start with presenting the basic notions of (co)homomology of simplical complexes (which requires only basic linear algebra over the field of order 2) and then we will indicate its relevance for several topics in computer science and combinatorics: 1) Property testing. 2) Quantum error correcting codes (where triangulation of some 4-dim hyperbolic manifolds lead to such codes with unexpected parameters) 3) High dimensional expanders. 4) Random simplical complexes.