# Right tight function restriction expression

From Groupprops

Template:Function restriction expression property

## Definition

### Symbol-free definition

A function restriction expression is said to be **right tight** if the right side cannot be made any stronger for the same choice of left side.

### Definition with symbols

A function restriction expression is said to be **right tight** if given such that , we have .

## Facts

For any given choice of left side, there is a unique choice of right side that makes the expression right tight. The operation of transforming an arbitrary function restriction expression, to the one with this right side, is termed right tightening.