1. Proveif ?∈?,then1+(−1)!(2?−1)is a multiple of four
2. If?={∅,{∅}}, which of the following statements is true:
a.∅⊆?
b.{∅}⊆?
c.{∅}∈?
3. Provide a grammar for all bit strings that start with exactlyone zero followed by even number of 1’s.
