Here ={a, b, c, d}

Convert state diagram below to an equivalent regular expression using the method described below, include intermediate steps:

Input state diagram must have exactly one final state, if not then modify by adding new final state with epsilon transitions from original final state.

Eliminate states one by one (excluding start and final) until only a two state diagram remains (when eliminating a state X need to add all transitions to all pairs of states connected to X: note that two states Y, Z can be the same state)

Intermediate steps should be generalized state diagrams where transitions are labeled by regular expressions.

a 1 b 2 b 3 d