Gil Kalai (Hebrew: גיל קלאי; born 1955) is an Israeli mathematician and computer scientist.

[1] Kalai received his PhD from Hebrew University in 1983, under the supervision of Micha Perles,[2] and joined the Hebrew University faculty in 1985 after a postdoctoral fellowship at the Massachusetts Institute of Technology.

[1] He is known for finding variants of the simplex algorithm in linear programming that can be proven to run in subexponential time,[4] for showing that every monotone property of graphs has a sharp phase transition,[5] for solving Borsuk's problem (known as Borsuk's conjecture) on the number of pieces needed to partition convex sets into subsets of smaller diameter,[6] and for his work on the Hirsch conjecture on the diameter of convex polytopes and in polyhedral combinatorics more generally.

In any quantum computer at a highly entangled state there will be a strong effect of error-synchronization.

[9][non-primary source needed] Kalai was the winner of the 2012 Rothschild Prize in mathematics.