Compare two unsigned 4-bit numbers using only logic gates (AND, OR, NOT, XOR): no relational operators. Work from the MSB down: a is greater when, at the first bit where they differ, a has the 1.

Inputs: a and b, 4 bits each.
Outputs: gt (a > b), eq (a == b), lt (a < b). Exactly one is 1.

The testbench applies all 256 pairs. It checks the outputs, not the operators you used; the gates-only rule is the exercise.