isogeny (countable and uncountable, plural isogenies)
The condition of being isogenous.
(algebraic geometry, category theory) An epimorphism of group schemes that is surjective and has a finite kernel.
,
so that is in turn the dual isogeny of its dual . Isogeny of complex tori, rather than isomorphism, will turn out to be the appropriate equivalence relation in the context of modular forms.
In some contexts, (e.g, universal algebra), an epimorphism may be defined as a surjective homomorphism, and the definition of isogeny may change accordingly. In the broader context of category theory, however, this substitution is not made, because the definitions are not precisely identical. (A surjective homomorphism is always an epimorphism, but the reverse is not always true. See )
Source: Wiktionary
2 July 2025
(noun) getting something back again; “upon the restitution of the book to its rightful owner the child was given a tongue lashing”
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