Let a= {a, b} and let s be the set of all strings with alphabet a. define f: s -> s as follows:
for any string %u03c3, define f(%u03c3) = the string resulting by replacing all a's by b's and all b's by a's in the string.
select all true statements below:
f is an onto function
for all input strings x, f(x)= f(f(x))
f is a one-to-one function
f has an inverse