Equations des contraintes

[invitec998f71d]

Bonjour

En mecanique et particulierement en MQ je vois apparaitre des choses comme;
la fonction obeit aux contraintes de jauge ou dans une equation en cosmologie
PHI verifie l'équation de contrainte H PHI = 0
Je cherche en vain un lien qui explique comment ces contraintes apparaissent.
Il semble que ces equations sont liees a certaines symetries de l'hamiltonien...?
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[invitec998f71d]

Je fais remonter cette question restee sans reponse au cas ou...

[invitec998f71d]

Un autre exemple:
In theoretical physics, it is often important to study theories with the diffeomorphism symmetry such as general relativity. These theories are invariant under arbitrary coordinate transformations. Equations of motion are generally derived from the requirement that the action is stationary. There are special variations that are equivalent to spatial diffeomorphisms. The invariance of the action under these variations implies non-dynamical equations of motion i.e. constraints. These equations must be satisfied or, at least, they must annihilate the physical states in a quantum version of the theory.

c'est comprehensible jusqu'à "non dynamique cad contraint"