In Maple, constants are not automatically considered to be constant functions, and therefore  does not automatically simplify to Pi whereas  does simplify to .  This procedure performs those simplifications.

Candidates for simplification are symbols in the expression sequence constants which are not themselves procedures or for which there does not exist an evalf function.

Note: In order to perform this simplification using the syntax simplify(expr, 'constants'), it is mandatory that the keyword 'constants' be enclosed with quotes, to prevent the premature evaluation of this keyword to the list of Maple constants

constants;