SemiBase
← [6, 8866][6, 8868] →

[6, 8867] finitely based

monoidnot self-dualother generated proof

[6, 8867] is a monoid with 4 idempotents and an identity element, 6. It is finitely based: 2 identities define its variety, which 2 other semigroups of order six also generate.

Cayley table

·123456
1113111
2113112
3331333
4123454
5123455
6123456

The product of the row element and the column element, numbered as in Smallsemi. Blue: idempotents on the diagonal.

Structure

Smallsemi
SmallSemigroup(6, 8867)
Idempotents
1, 4, 5, 6
Zero
none
Identity
6
Nilpotent
no
Commutative
no
Regular
no
Group
no
𝒥-classes
4
Rank
5, generated by {2, 3, 4, 5, 6}
Self-dual
no: the class also stands for the opposite semigroup, with the transposed table

Identity basis

Shortest known basis: 2 identities irredundant

  1. x² ≈ x⁴
  2. xyx ≈ yx²

Irredundant: none of these identities follows from the others; for each, a semigroup satisfies the others but not it. Obtained from a basis certified in Lean by removing identities that follow from the others, with the prover Vampire; the equivalence rests on Vampire's proofs, not on Lean. Shortest known, not known to be minimal.

Basis certified in Lean: 2 identities

  1. x² ≈ x⁴
  2. xyx ≈ yx²

Lean proof

Endpoint theorem: SemigroupBasis.Generated.Order6MissingAuthenticatedRootsV3.S6_8867.opposite_basis

BasisFor Generated.Order6MissingAuthenticatedRootsV3.S6_8867.table.semigroup
  (reversedBasis Generated.Order6MissingAuthenticatedRootsV3.Sources.S6_11390.basis)
Table
The theorem is about the opposite semigroup, with the transposed table; read backwards, its basis is the basis of this table shown above.
Method
other generated proof. A machine-generated proof that builds on semigroups certified earlier: an adapter or wrapper of a transfer found by the campaign's search.
Size
Checking this class alone compiles 204 Lean files with 115,896 lines: the endpoint theorem and everything it imports, the shared library included. Of these, 19,420 lines are used by the proof of this class and of no other.
Census
SemiBase.Census.S6_8867 checks that the theorem is about the table of this class and concludes Classified; SemiBase.Catalogue.Order6.S6_8867 is the table, with the elements numbered 0 to 5.

Variety

[6, 8867] generates the variety V[8867]; 2 other semigroups of order six generate it too, and 3,617 semigroups of order six lie in it. [6, 8867] lies in 2 of the 505 varieties of the census, those whose basis it satisfies.

Directly above
V[8924]
Directly below
V[7382] V[8827] V[8866]

V[8867] in the inclusion graph, with the varieties above and below it.

Generating the same variety

[6, 9011] [6, 11390]

Nearby tables

Semigroups whose Smallsemi table differs from this one in one or two entries (row, column), as the tables are listed, not up to renumbering.