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Hereditarity of closure operators and injectivity

Gabriele Castellini, Eraldo Giuli (1992)

Commentationes Mathematicae Universitatis Carolinae

A notion of hereditarity of a closure operator with respect to a class of monomorphisms is introduced. Let C be a regular closure operator induced by a subcategory 𝒜 . It is shown that, if every object of 𝒜 is a subobject of an 𝒜 -object which is injective with respect to a given class of monomorphisms, then the closure operator C is hereditary with respect to that class of monomorphisms.

Making factorizations compositive

Reinhard Börger (1991)

Commentationes Mathematicae Universitatis Carolinae

The main aim of this paper is to obtain compositive cone factorizations from non-compositive ones by itereration. This is possible if and only if certain colimits of (possibly large) chains exist. In particular, we show that (strong-epi, mono) factorizations of cones exist if and only if joint coequalizers and colimits of chains of regular epimorphisms exist.

Natural weak factorization systems

Marco Grandis, Walter Tholen (2006)

Archivum Mathematicum

In order to facilitate a natural choice for morphisms created by the (left or right) lifting property as used in the definition of weak factorization systems, the notion of natural weak factorization system in the category 𝒦 is introduced, as a pair (comonad, monad) over 𝒦 2 . The link with existing notions in terms of morphism classes is given via the respective Eilenberg–Moore categories.

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