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Section A.2 Algebraic Structures

Subsection Grouplike Structures

Definition A.5.

Let \(*\) be a binary operation on a set \(S\text{.}\) We define the following:
  • The pair \((S,*)\) is called a magma.
  • A semigroup is an associative magma.
  • A monoid is a semigroup with an identity element.
  • A group is a monoid with inverses.
  • An abelian group is a commutative group.

Definition A.6.

Let \(*\) be a partial binary operation on a set \(S\text{.}\) We define the following:
  • The pair \((S,*)\) is called a partial magma.
  • A semigroupoid is an associative partial magma.
  • A small category is a semigroupoid with an identity element.
  • A groupoid is a small category with inverses.

Subsection Ringlike Structures

Definition A.7.

Subsection Latticelike Structures

Definition A.8.