Pasting lemma

Two continuous functions can be glued together to create another continuous function

In topology, the pasting or gluing lemma, and sometimes the gluing rule, is an important result which says that two continuous functions can be "glued together" to create another continuous function. The lemma is implicit in the use of piecewise functions. For example, in the book Topology and Groupoids, where the condition given for the statement below is that and

This keyword could refer to multiple things. Here are some suggestions: