Submodules of a module #
In this file we define
Submodule R M: a subset of aModuleMthat contains zero and is closed with respect to addition and scalar multiplication.Subspace k M: an abbreviation forSubmoduleassuming thatkis aField.
Tags #
submodule, subspace, linear map
A submodule of a module is one which is closed under vector operations. This is a sufficient condition for the subset of vectors in the submodule to themselves form a module.
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The actual Submodule obtained from an element of a SMulMemClass and AddSubmonoidClass.
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Construct a submodule from closure under two-element linear combinations. I.e., a nonempty set closed under two-element linear combinations is a submodule.
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Copy of a submodule with a new carrier equal to the old one. Useful to fix definitional
equalities.
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Submodule R M almost never has decidable equality.
Given an element m ≠ 0 in M, Submodule R M has decidable equality iff
all propositions are decidable. We add a global instance that Submodule R M has decidable
equality, coming from the choice axiom, so that we don't have to provide
[DecidableEq (Submodule R M)] arguments in lemma statements.
This can't be an instance because Lean wouldn't know how to find R, but we can still use
this to manually derive Module on specific types.
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Reinterpret a submodule as an additive subgroup.