Constrained optimization exact introduction

Minimize[E^E^x - x, x]

{2.3303661247616807, {x -> -0.5671432904048208}}

MaxValue[{Sqrt[x^2 + y^2], x^4 + 3y^4 ≤ 7}, {x, y}]

0

MaxValue[{Sqrt[x^2 + y^2], a x^2 + b y^2 ≤ 1}, {x, y}]

0