commutative_semigroup

..admonition:: Additive Semigroup

Mathematically an Additive Semigroup is a set S along with an associative binary operation add: S X S -> S.

Important

Contract: Group initializer parameters must have

  • add closed, commutative and associative on reps

class boring_math.abstract_algebra.algebras.commutative_semigroup.CommutativeSemigroup

Bases: BaseSet, Generic

Parameters:

  • add – Closed commutative and associative function reps.

  • narrow – Narrow the rep type, many-to-one function. Like choosing an element from a coset of a group.

__init__(add: Callable[[H, H], H], narrow: Callable[[H], H] | None = None) → None
Parameters:

  • add – Closed commutative and associative function reps.

  • narrow – Narrow the rep type, many-to-one function. Like choosing an element from a coset of a group.

__call__(rep: H) → CommutativeSemigroupElement

Add the unique element to the commutative semigroup with the given, perhaps narrowed, rep.

Parameters:

rep – Representation to add if not already present.

Returns:

The unique element with that representation.

__eq__(right: object) → bool

Compare if two algebras are the same concrete algebra.

Parameters:

right – Object being compared to.

Returns:

True only if right is the same concrete algebra. False otherwise.

narrow_rep_type(rep: H) → H

Narrow the type with a concrete algebra’s many-to-one type “narrowing” function.

Parameters:

rep – Hashable value of type H.

Returns:

The narrowed representation.

class boring_math.abstract_algebra.algebras.commutative_semigroup.CommutativeSemigroupElement

Bases: BaseElement, Generic

__init__(rep: H, algebra: CommutativeSemigroup[H]) → None
__str__() → str
Returns:

str(self) = CommutativeSemigroupElement<rep>

__add__(right: Self) → Self

Add two elements of the same concrete algebra together.

Parameters:

other – Another element within the same algebra.

Returns:

The sum self + other.

Raises:

  • ValueError – If self and other are same type but different concrete algebras.

  • TypeError – If Addition not defined on the algebra of the elements.

  • TypeError – If self and right are different types.

__radd__(left: Self) → Self

When left side of addition does not know how to add right side.

Parameters:

other – Left side of the addition.

Returns:

Never returns, otherwise left.__add__(right) would have worked.

Raises:

TypeError – When right side does not know how to add the left side to itself.

__mul__(n: object) → Self

Repeatedly add an element to itself n > 0 times.

Parameters:

n – Object, usually a positive int or action.

Returns:

If n: int then self added to itself n times else NotImplemented.

Raises:

  • ValueError – When n <= 0.

  • ValueError – If self and other are same type but different concrete algebras.

  • TypeError – If an add method was not defined on the algebra.

  • TypeError – Element multiplication attempted but algebra is not multiplicative.

__rmul__(n: int) → Self

Repeatedly add an element to itself n > 0 times.

__call__() → H

Warning

A trade off is being made in favor of efficiency over encapsulation. An actual reference to the wrapped rep is returned to eliminate the overhead of a copy.

Returns:

The narrowed representation wrapped within the element.

__eq__(right: object) → bool

Compares if two elements, not necessarily in the same concrete algebra, contain equal representations of the same hashable type.

Warning

Any sort of difference in rep narrowing is not taken into consideration.

Parameters:

right – Object to be compared with.

Returns:

True if both are elements and the reps compare as equal and are of the same invariant type.