A Galois connection between preorders \(P\) and \(Q\), and the left and right adjoints of a Galois connection
A pair of monotone maps \(P \xrightarrow{f} Q\) and \(Q \xrightarrow{g} P\) such that:
\(f(p) \leq q \iff p \leq g(q)\)
\(f\) is left adjoint and \(g\) is right adjoint of the Galois connection.