Tarski's automorphsisms
November 14, 2024I first came across Albert Lautman (nLab) after reading Fernando Zalamea’s remarks on his importance to structural mathematics in Synthetic philosophy of contemporary mathematics.
While reading …
Sheaves are presheaves with an equalizer diagram
October 26, 2024A sheaf on a topological space $ X $ can be defined as a presheaf $ F: \text{Open}(X)^{\text{op}} \to \mathbf{Set} $ such that for any open covering $ { U_i } $ $ (i \in I) $ of an open set $ U $, the …
Free semimodules and their examples
August 22, 2024abstract. This project covers free semimodules and their examples. We define various algebraic structures via $\Omega$-algebras (from universal algebra) with an emphasis on semimodules. We continue to …
Monomorphisms and epimorphisms
December 17, 2022The classes of monomorphisms, epimorphisms, bimorphisms, split monomorphisms, and split epimorphisms are closed under composition and contain all isomorsphisms. To show these classes are closed under …
hom-Sets
December 15, 2022Let $\mathbb{C}$ be a fixed category.
Consider a morphism $f:A\to B$ in $\mathbb{C}$ then, for any object $X$ in $\mathbb{C}$, …
Describing difficult spaces
December 14, 2022The idea behind this curatorial project is to give artists a prompt describing a space that is difficult to visualise, and ask them to come up with a way of describing that space whether that be a …
M-sets and Yoneda for monoids
July 15, 2022The Yoneda lemma says that for a category $\mathbb{C}$, an object $C$ in $\mathbb{C}$, and a functor $S:\mathbb{C}\to\textbf{Sets}$, $\operatorname{Nat}(\operatorname{hom}(C,-),S)$ is in bijection …
Free algebras by means of a universal property
June 27, 2022Consider a vector space $V$, when $X$ is a basis of $V$, we say that $V$ is a free vector space on $X$ 1. For any vector space $V$ and $W$ and a basis $X$ of $V$, if there is a map $f:X\to W$ then …
An algebraic category is defined to be any full subcategory of $\textbf{Alg}(\Omega)$, the catgeory of all $\Omega$-algebras. We can define various algebraic structures as algebraic categories. For …
Groupoids and skeletons of monoids and preorders
June 14, 2022A monoid $(M,e,m)$, where $M$ is a set, $e$ an element of $M$, and $m$ an associative binary operation on $M$, can be viewed as a single object category. Take $M_0 = \{M\}$ or $M_0 = \emptyset$ and …
Exercises in category theory
June 14, 2022(Last updated: December 2022)
I will be making a series of posts that contains edited versions of some of the short answers I submitted for my category theory course at the University of Cape Town. …
Over the past couple days I have been watching Tadashi Tokieda’s Topology and Geometry lectures, given at AIMS.
I thought they would help me prepare for my first point-set topology course. The …