How can I make a string empty again after going through different states in a non deterministic finite automata?

Question

For example I have several states I will name A, B and C.

A allows 1,0 and loops. When it enters state B, is it possible that everything will be empty again before going to C? If yes, how?

Answer 1

In general finite automata is like decision making type.It can tell whether the given string is recognized by the automata or not.The major draw back of finite automata is that it can't recognize the previously given input.so to enhance it we are going for push down automata(pda).In pda we have stack to store the input symbols.There also we can push or pop only one element at a time.If you want to pop all elements when it enters state B then use a loop to pop all elements of the stack until stack becomes empty