theorem :: TOPALG_1:36

for T being non empty pathwise_connected TopSpace
for a1, b1, c1, d1, e1 being Point of T
for A being Path of a1,b1
for B being Path of b1,c1
for C being Path of c1,d1
for D being Path of d1,e1 holds (A + (B + C)) + D,(A + B) + (C + D) are_homotopic