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A one-to-one mapping is a bijection. A many-to-one mapping is a "general function" and might also be a "surjective function".

Is there a similarly technical name for a many-to-many mapping, or should I just write "many-to-many" whenever describing such a thing. Same question for a "one-to-many" mapping (perhaps "inverse general function")?

EDIT: For what I mean by a "many-to-many" mapping:

Set 1: A, B, C, D
Set 2: W, X, Y, Z

A maps to W
B maps to W and X
C and D map to Y and Z (many-to-many relationship)
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What does many-to-many even mean? – Cameron Williams Jan 14 '14 at 3:08
In this case, multivalued is probably the right term, as janmarqz suggests. – Cameron Williams Jan 14 '14 at 3:13
up vote 8 down vote accepted

Another common name is relation.

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Thanks! Can you double check your link? I think you had a little copy-paste mishap. – Kevin Jan 14 '14 at 4:14
@Kevin thanks! Yes, I was trying to cut and paste on a tablet and I'm not very good at it. – rschwieb Jan 14 '14 at 12:02

Multivalued function is used. In places like this you can see more details and many other technical situations.

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