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Colloquia

The C^3 problem: locally testable codes with constant rate and constant distance

Alex Lubotzky (Hebrew University and IAS)

Location:  Hill Center Room 705
Date & time: Wednesday, 17 November 2021 at 3:30PM - 4:30PM

Abstract:  An error-correcting code ( LTC) is locally testable if there is a random tester that reads only a constant number of bits of a given word and decides whether the word is in the code, or at least close to it.  A long-standing problem asks if there exists such a code that also satisfies the golden standards of coding theory: constant rate and constant distance. Random codes are not LTC !

 We construct such codes based on what we call (Ramanujan) Left/Right Cayley square complexes. These 2-dimensional objects seem to be of independent interest.  Joint work with I. Dinue, S.Evra, R. Livne and S. Mozes. The talk will be self-contained.