automata and formal languages

4. Fill in the blanks. (a) In a - (b) The grammar, the right hand side of a rule cannot have more than two symbols. algorithm can be used to prove that the class of context-free languages is a subclass of P. (c) The class of sliding block puzzles includes a number well-known puzzles avaiable at toy stores, including Sam Lloyd's 15 puzzle, Rush Hour, and Rubik's Cube. The smallest complexity class which contains all sliding block puzzles is known to be