Galois connection

noun1

1. •
   A type of correspondence between partially ordered sets (posets), also applicable to preordered sets.

   • Define maps G:A→B and F:B→A by G(a)=y!∈!Y|∀x!∈!axρy and F(b)=x!∈!X|∀y!∈!bxρy. Then (F,G) is called a Galois connection of the first kind. — 1986