On expected factors in reduced decompositions in type BB

The expected number of Yang–Baxter moves appearing in a reduced decomposition of the longest element of the Coxeter group of type BnBn is computed to be 2−4/n2−4/n. For the same element, the expected number of 0101 or 1010 factors appearing in a reduced decomposition is 2/(n2−2)2/(n2−2).