Exact Sequences - functions on longright arrows
In exact sequences, a convenient notation is to have a function symbol like on a longrightarrow.
I have given an example of this in the attachment so it is clear what notation I am requesting help with - see attachment "Exact Sequences - Latex Question"
I have also provided an attachment showing the start of Section 10.5 (Exact Sequences) of Dummit and Foote where there are a number of examples of the terminology I am hoping to use in Latex encoded postings.
If someone can help me with this problem I would be most grateful