For a homework I have to implement diferent circuits with AND, NOR, NAND, OR using two-level implementation and using real 2-input implementation. I've figured how to do this for all gates except NOR.

For all gates except NOR the following applies:

2-level implementation=2-input implementation

X (gate) Y (gate) Z = (X(gate)Y) (gate) Z

but

X (NOR) Y (NOR) Z ≠ (X(NOR)Y) (NOR) Z

how would I go from a 2-input NOR circuit to a 2-level (possibly 3 input NOR) circuit? i.e from the left hand side to an equivalent right hand side.

Thanks.