# "correspondence from A to B" or "correspondence between A and B"

Usually we are familiar with the usage:

"correspondence between A and B"

but can we also use:

"correspondence from A to B" ?

Does the 2nd case grammatically work, too?

Here the correspondence is not specific to the mailing correspondence, but to the math function or the physical relation.

• From A to B would designate only the letters &c which A wrote, not letters written by both A and B. Commented Jul 18, 2014 at 16:35
• I find that the 2nd case is used here: "In category theory, a correspondence from C to D" in math. Commented Jul 18, 2014 at 16:36
• Ah. If you are speaking of mathematical correspondence, ignore my comment. You may have to migrate this question to Mathematics if there is no one active here who is familiar with sophisticated mathematical usage. Commented Jul 18, 2014 at 16:40
• What StoneyB said. From Basic Algebra II: Second Edition "If (I) is a correspondence from A to B, the inverse correspondence <I>_1 from B to A is the set of pairs (b, a) such that [blah blah]. That all goes over my head, but obviously it suggests there's a domain-specific usage involved. Usually (and for the purposes of ELL), we speak of correspondence between [two people/things which correspond in some way]. Commented Jul 18, 2014 at 16:47

There are two main meanings of correspondence that come to mind:

1. two things exacty lining up
2. messages exchanged between two things

The first case includes things like

• "His rise in blood pressure exactly corresponded to when he eat salty pretzels." (So "there is a correspondence between his rise in blood pressure and when he eats salty pretzels.")
• "The complex numbers correspond to the set of 2x2 real matrices satisfying such and such properties."

And the second

• "The correspondence between Hardy and Ramanujan regarding prime numbers."