Weak Adjoint Functors.
Weak subobjects and weak limits in categories and homotopy categories
Weakly hereditary regular closure operators
Weakly locally presentable categories
Weakly monadic Boolean extension functors
What are sifted colimits?
What is a double central extension ? (the question was asked by Ronald Brown)
When are induction and coinduction functors isomorphic?
When is a cogenerator in a topos ?
When spectra of lattices of -ideals are Stone-Čech compactifications
Let be a completely regular Hausdorff space and, as usual, let denote the ring of real-valued continuous functions on . The lattice of -ideals of has been shown by Martínez and Zenk (2005) to be a frame. We show that the spectrum of this lattice is (homeomorphic to) precisely when is a -space. This we actually show to be true not only in spaces, but in locales as well. Recall that an ideal of a commutative ring is called a -ideal if whenever two elements have the same annihilator and...
When the product-preserving functors preserve limits