a) Consider the full adder function: sum(c i-1, xi , yi ) = (ci , si ) Where xi , yi are the ith bits of the binary numbers X and Y, ci-1 is the carry in and the outputs are: ci , the carry out and si is the sum output. Write the equations of both ci and si in conjunctive normal form (CNF), i.e. in standard product of sums (SPOS). b) As a result of a) above, design the corresponding circuit for the full adder, using only the NOR gates..