# Math Help - Inclusion map

1. ## Bi-module

Hi

The definition of a sub-algebra goes as follows:

"A sub-algebra is an R-algebra B that is a subset of an algebra A such that the inclusion mapping from B to a A is a homomorphism"

I've got the definition for an inclusion mapping from wiki. and other sources.
Can someone help me with the explanation of the role played by the inclusion map in this particular definition?