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5 votes
0 answers
149 views

In what algebraic categories do finitely presentable objects form a dense cogenerator?

For each $C$ locally finitely presentable category, the full subcategory of finitely presentable objects $C_{fp}$ is a dense generator, i.e. the natural functor $C \to \mathrm{PSh}(C_{fp})$ is a full ...
Arshak Aivazian's user avatar
8 votes
1 answer
584 views

Is the Cartesian product of two finitely presented objects finitely presentable?

Let $C$ be a locally finitely presented category, $A, B$ are two finitely presented (synonym: compact) objects in it. Is it true that $A \times B$ is finitely representable? At least I have looked at ...
Arshak Aivazian's user avatar
6 votes
3 answers
523 views

Contramodule as direct limit of its finitely generated subcontramodules

$\DeclareMathOperator\Hom{Hom}$Let $K$ be a field. Let $C$ be a $K$-coalgebra. A contramodule $M$ over $C$ is a $K$-space with a $K$-linear map $\pi_M:\Hom_K(C,M)\longrightarrow M$ such that $\pi_M \...
Sam's user avatar
  • 383
7 votes
1 answer
563 views

Characterisation of essentially algebraic theories as monads

The following correspondence between algebraic theories and monads on $\mathbf{Set}$ is well-known (see, for example, Algebraic Theories: A Categorical Introduction to General Algebra). The ...
varkor's user avatar
  • 10.7k
4 votes
1 answer
362 views

Locally presentable categories

Under category Let $C$ be a locally presentable category, and let $c$ be an object of $C$. Lets denote by $C^{/c}$ the under category, objects are maps $c\rightarrow x$ and morphisms are the evident ...
Let's user avatar
  • 511