# Questions tagged [semigroups-and-monoids]

A semigroup is a set $S$ together with a binary operation that is associative. Examples of semigroups are the set of finite strings over a fixed alphabet (under concatenation) and the positive integers (under addition, maximum, or minimum). A monoid is a semigroup with a neutral element. Of course, any group is also a monoid/semigroup.

**3**

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### Lie monoids as monoids internal to the category of smooth manifolds?

**0**

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### Looking for a characterization of 'P2-monoids' and related structures

**3**

**3**answers

### Surjective monoid homomorphism $\text{End}(B)\to \text{End}(A)$ given surjection $g:B\to A$

**3**

**1**answer

### Can one turn finite-dimensional vector subspaces into a cancellative semigroup?

**2**

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### Non-commutative version of the order dimension of a poset

**6**

**1**answer

### Identities of finite inverse semigroups

**5**

**3**answers

### Is the class of power-associative binars finitely axiomatizable?

**5**

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### Maximal number of commuting functions of a finite set

**0**

**1**answer

### The rank of a semigroup

**12**

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### Combinatorial proof of invertibility of a symmetric matrix associated to the ring of matrices over a finite field

**2**

**1**answer

### Centralizer of a single element in the monoid of self-maps of a set

**11**

**2**answers

### For what sets $X$ do there exist a pair of functions from $X$ to $X$ with the identity being the only function that commutes with both?

**0**

**0**answers

### A semifield of characteristic zero may have a finite number of elements

**8**

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### Are most semigroups nilpotent of degree 3?

**3**

**1**answer

### Question on monoid algebras

**2**

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### Bijection between monoid of nilpotent decreasing self-maps and local subsemigroup

**23**

**3**answers

### What spaces $X$ do have $\text{End}(X) \cong \text{End}(\mathbb{R})$?

**5**

**3**answers

### Spaces with unique endomorphism monoids

**3**

**1**answer

### Quasi-isometries and E-unitary inverse semigroups

**5**

**1**answer

### Ascending sequences of idempotents in inverse semigroups

**2**

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### On the number of connected functional digraphs recoverable from the preimage set size structure

**2**

**1**answer

### Additivity of the upper Banach density

**3**

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### What is a “cusp” (“кусок”) in relation to Guba's embedding theorem?

**2**

**0**answers

### Is the natural action of the monoid of endomorphisms is a complete invariant for group?

**2**

**1**answer

### Classification of associative polynomial functions

**14**

**1**answer

### Associativity may fail by little?

**1**

**1**answer

### Closed submonoid of $(\mathbb{C}^*)^n$

**4**

**1**answer

### Closed cobounded additive submonoid of $\mathbb{R}^n$

**1**

**1**answer

### What is the minimal possible size of a subset of this semigroup satisfying the following conditions?

**7**

**2**answers

### Counting nilpotent self-maps of $\{1,\dots,n\}$ with image of a given cardinal

**6**

**1**answer

### Comonoids in the category of monoids

**1**

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### Compute irreducibles of monoid

**0**

**1**answer

### Continuous semigroup homomorphism of composition to additive structure

**17**

**2**answers

### Monoids of endomorphisms of nonisomorphic groups

**1**

**1**answer

### Internal commutative monoid gives commutative monad

**3**

**1**answer

### Joint spectral radius of $\{M,M^T\}$

**3**

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### Cancellativity of a particular $2$-generated monoid presented by an infinite number of relations

**2**

**0**answers

### Are there finitely-presented astral monoids?

**0**

**0**answers

### $m$-potent elements in $N(C_n)$

**5**

**0**answers

### Generating the monoid of injective endomorphisms of the free group

**2**

**1**answer

### Define a homomorphism of a set of graphs to its power set

**0**

**1**answer

### Multiplicative monoid of ring modulo units

**6**

**0**answers

### Generalization of pseudogroups

**8**

**2**answers

### Is the equational theory of groups axiomatized by the associative law?

**5**

**1**answer

### A characterisation of faces of rational polyhedral cones

**5**

**1**answer

### Which homotopy types can be realized as the classifying space of a right-cancellative discrete monoid?

**8**

**1**answer

### Who invented Monoid?

**5**

**1**answer

### Topological category of topological monoids / operads

**4**

**1**answer

### Characterization of Archimedean linearly ordered monoids

**6**

**0**answers