From Rotman's Algebraic Topology:
I'm having trouble proving that this is a weak fibration. I can see that diagonal map for the commutative diagram of a fibration must be of the form $\tilde G(\bar t, t) = (G(\bar t, t), ? )$, but I'm not sure how to proceed to find the ? component.
I'm not really understanding how the hint can be applied either.
Anyone have any ideas?