1. Write a regular expression for the set of strings using the alphabet {a,b,c} that have each b immediately preceded by an a. Note that I said "preceded", not "followed". Also note that a string need not have any b's at all. For the grammar --> --> E E E E E/E EE -E LU --> id give a parse tree and a leftmost derivation for the input -id*id/id*id Is the grammar ambiguous? If so, show that it is