Commit 2023-08-01 15:12 d4d88d3b

refactor(AlgebraicGeometry/EllipticCurve/Weierstrass): change the variableChange into a structure (#5841) Main changes:

• Change the variableChange (was u r s t everywhere) into a structure VariableChange.
• Add id, comp and inv to VariableChange and prove that it form a group and acts on the set of elliptic curves to the left.
• Add baseChange to VariableChange, prove the compatibility of it with base change of elliptic curves.
• Prove that if the ring homomorphism is injective, then baseChange of VariableChange and elliptic curves are injective (NB: We don't say anything about elliptic curves modulo isomorphism yet!)
• Prove that baseChange of VariableChange is a group homomorphism