can you please explain how the regular expression for part (a) was obtained?

LGORITHMS ollows Problem 761 236 Consider the Turing marhine: such that: (a,b ?= (B,a,b,9); y final state uch regular and ? is defined by the following transition set (q, c. , y, ?.RI a. B,r, B, LI Ir. a,r, a, L [s, a, s, u, L] ral Al- t, a, t, a, L v, B, v, B, R (B is the designated blank symbol. M has an one-way infinite tape and accepts by final state.) (a) Write a regular expression that defines the set of strings on which M diverges. If such regular expression does not exist, prove it. Answer: a ba ba b(a Ub) es(b) Write a regular expression that defines the set of is " answer akes ex- strings on which M halts and accepts. If such regular expression docs not exist, prove it. Answer 0 (c) Write a regular expression that defiues the set of