Right tight restriction formal expression

Definition

Symbol-free definition

A restriction formal expression for a subgroup property is termed right tight if the right side cannot be made weaker for the same choice of left side. In other words, it does not possess any proper right tightening.

Definition with symbols

A restriction formal expression $a$ → $b$ is termed right tight if there is no property $c$ other than $b$ for which $c$ ≤ $b$ and $a$ → $b$ = $a$ → $c$.