theorem :: TOPALG_4:18
for S, T being non empty TopSpace
for s1, s2 being Point of S
for t1, t2 being Point of T
for l1, l2 being Path of [s1,t1],[s2,t2]
for H being Homotopy of l1,l2
for p, q being Path of t1,t2 st p = pr2 l1 & q = pr2 l2 & l1,l2 are_homotopic holds
pr2 H is Homotopy of p,q