Constant function

From Maths
Jump to: navigation, search
Stub grade: D
This page is a stub
This page is a stub, so it contains little or minimal information and is on a to-do list for being expanded.The message provided is:
Not important just good to have

Definition

Let [ilmath]A[/ilmath] and [ilmath]B[/ilmath] be sets and [ilmath]f:A\rightarrow B[/ilmath] be any function between them. We call [ilmath]f[/ilmath] a "constant function" if:

  • [ilmath]\exists b\in B\forall a\in A[f(a)=b][/ilmath]
    • In words: every [ilmath]a\in A[/ilmath] is sent to the same [ilmath]b\in B[/ilmath] by [ilmath]f[/ilmath].

We may write [ilmath]f[/ilmath] as:

  • [ilmath]f:A\rightarrow B[/ilmath] given by [ilmath]f:a\mapsto b[/ilmath]

Terminology

  • Constant map and constant mapping are obviously also used.
  • Trivial map might be used to describe a constant map (and I am sure I have seen it) but this is rare and ill-advised.

Notes

References

Grade: D
This page requires references, it is on a to-do list for being expanded with them.
Please note that this does not mean the content is unreliable, it just means that the author of the page doesn't have a book to hand, or remember the book to find it, which would have been a suitable reference.
The message provided is:
This terminology is... A-level, possibly earlier, and doesn't really need a page. So finding references will be difficult anyway as who would bother to write it!