theorem Th33: :: TOPALG_1:33

for X being non empty TopSpace
for a, b, c, d, e being Point of X st a,b are_connected & b,c are_connected & c,d are_connected & d,e are_connected holds
for A being Path of a,b
for B being Path of b,c
for C being Path of c,d
for D being Path of d,e holds ((A + B) + C) + D,A + ((B + C) + D) are_homotopic