What is "relative pseudo-complement"

n. (context mathematics English) The residual operation of a Heyting algebra when considered as a residuated lattice whose monoid operation is the meet operation. Equivalently, the ''relative pseudo-complement'' of ''a'' with respect to ''b'' is the supremum of the set of all ''z'' such that $z\; wedge\; a\; leqslant\; b$, where $wedge$ denotes the meet operation of the given Heyting algebra.