The monomer-dimer constant of the square lattice
Find a closed form for the entropy per site of monomer-dimer configurations on the square lattice, h ≈ 0.6627989727.
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The hard-square entropy constant
Find a closed form for the hard-square entropy constant κ ≈ 1.5030480825, the growth rate of independent sets in the square grid.
A binary code of length 21 with minimum distance 10
Construct a binary code of length 21 and minimum distance 10 with 43 words, beating the record of 42 that has stood since 1989.