[ToC]

 

A. T. Fomenko, D. B. Fuchs, and V. L. Gutemacher, Homotopic Topology, Akademiaia Kiado, Budapest, 1986

THE NECESSITY OF "BEING SEWN" IS NOT CLEAR FROM THIS FIGURE

Recommended by Tayyba Kanwal

Mappings f and f1 can be "sewn" together in the following way.