Base change of a free module #
Base change along a morphism of commutative monoid objects sends
the free module on an object to the free module over the new base:
B ⊗[A] (A ⊗ V) ≅ B ⊗ V as B-modules.
baseChangeFreeHom/baseChangeFreeInv: the two carrier maps, descending multiplication throughφand inserting the unit ofArespectively.baseChangeFreeIso: the isomorphismbaseChangeMod φ (freeMod A V) ≅ freeMod B Vin the category ofB-modules.
Multiplying through φ twice is multiplying through φ once
after multiplying in A.
Multiplying in B before pushing through φ is multiplying
in B after.
The first module-tensor leg of the base change of a free module, at carrier atoms.
The comparison map coequalizes the two module-tensor legs, stated at carrier atoms.
The comparison map coequalizes the two module-tensor legs.
The comparison map from the base change of a free module to the free module over the new base.
Equations
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Instances For
Defining equation of the comparison map.
Defining equation of the comparison map.
The inverse comparison map: insert the unit of A.
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Instances For
The balance relation of the base-change projection on a free module, at carrier atoms.
The balance relation of the base-change projection on a free module, at carrier atoms.
Multiplying out and reinserting the unit of A returns the
projection: the retract identity behind hom ≫ inv = 𝟙.
The two comparison maps compose to the identity of the base change.
Inserting the unit of A and multiplying out through φ is
the identity of B ⊗ V.
The two comparison maps compose to the identity of the free module over the new base.
The comparison map intertwines the two B-actions, at carrier
atoms.
Defining equation of the B-action on the base change of a
free module, at carrier atoms.
The comparison map is B-linear.
The comparison map is B-linear.
The inverse comparison map is B-linear.
Base change of a free module: the base change along φ of
the free A-module on V is the free B-module on V, as an
isomorphism of B-modules.
Equations
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