delooping of the bicyclic monoid
Every monoid induces a category with a single object , morphisms given by the elements of , and composition given by the monoid operation. Some of the properties of this category depend on the specific monoid.In this entry, we take the monoid freely generated by subject to the relation , known as the bicyclic monoid and often denoted by . Every element of can be uniquely written as for .This category is a one-object version of the walking splitting, but its properties are completely different.
Satisfied properties
Assigned properties
- is small
- is countable
- is core-connected
- is skeletal
- is self-dual
- is Cauchy complete
- is core-thin
- is mono-regular
- has reflexive coequalizers
- is ℵ₁-accessible
Deduced properties
- is accessible
- has ℵ₁-filtered colimits
- has quotients of congruences
- has effective congruences
- is strongly connected
- has an extremal generator
- is balanced
- is essentially small
- is locally small
- is essentially countable
- is gaunt
- has coquotients of cocongruences
- has effective cocongruences
- has an extremal cogenerator
- is ℵ₁-coaccessible
- is epi-regular
- has coreflexive equalizers
- has an extremal generating collection
- is well-powered
- is locally essentially small
- is semi-strongly connected
- has a generator
- is coaccessible
- has ℵ₁-cofiltered limits
- has a cogenerator
- has an extremal cogenerating collection
- is well-copowered
- is connected
- has a generating collection
- is inhabited
- has a cogenerating collection
- is concretizable
Unsatisfied properties
Assigned properties
- is not retract-trivial
- does not have zero morphisms
- does not have cokernel pairs
- is not sifted
- does not have sequential colimits
Deduced properties*
- is not preadditive
- does not have biproducts
- does not have kernels
- does not satisfy CIP
- is not filtered
- does not have binary coproducts
- is not pointed
- is not normal
- is not regular-subobject-trivial
- is not locally finite
- is not one-way
- is not right cancellative
- does not have cokernels
- does not satisfy CSP
- does not have directed colimits
- is not conormal
- does not have pushouts
- does not have equalizers of cokernel pairs
- is not regular-quotient-trivial
- is not cosifted
- does not have kernel pairs
- does not have sequential limits
- is not unital
- is not additive
- is not abelian
- is not left cancellative
- is not finitely cocomplete
- does not have coequalizers
- is not ℵ₁-filtered
- does not have filtered colimits
- does not have directed limits
- does not have pullbacks
- does not have coequalizers of kernel pairs
- is not essentially finite
- is not subobject-trivial
- is not thin
- is not direct
- is not counital
- is not locally cocartesian coclosed
- is not cofiltered
- does not have binary products
- is not a groupoid
- does not have finite coproducts
- does not have wide pushouts
- is not coregular
- does not have pushout-stable regular monomorphisms
- is not quotient-trivial
- is not inverse
- is not finitely accessible
- is not Grothendieck abelian
- is not split abelian
- is not locally cartesian closed
- is not trivial
- is not discrete
- is not essentially discrete
- does not have disjoint finite coproducts
- is not distributive
- does not have exact filtered colimits
- does not have cartesian filtered colimits
- does not have filtered-colimit-stable monomorphisms
- is not extensive
- does not have a terminal object
- does not have sifted colimits
- does not have finite products
- does not have wide pullbacks
- is not regular
- does not have pullback-stable regular epimorphisms
- is not finite
- does not have binary powers
- does not have powers
- does not have countable powers
- is not an elementary topos
- is not a quasitopos
- is not co-Malcev
- does not have a coparametrized conatural numbers object
- is not locally poly-copresentable
- is not co-Grothendieck abelian
- is not dually multi-algebraic
- is not cocartesian coclosed
- is not cocomplete
- is not infinitary codistributive
- is not countably codistributive
- is not codistributive
- does not have exact cofiltered limits
- does not have cocartesian cofiltered limits
- is not finitely complete
- does not have equalizers
- is not ℵ₁-cofiltered
- does not have cofiltered limits
- does not have countable coproducts
- does not have connected colimits
- is not Barr-coexact
- does not have a quotient object classifier
- does not have a regular quotient object classifier
- does not have binary copowers
- does not have copowers
- does not have countable copowers
- is not an elementary cotopos
- is not a quasicotopos
- is not Malcev
- does not have a parametrized natural numbers object
- does not have a natural numbers object
- is not locally finitely presentable
- is not locally ℵ₁-presentable
- is not locally presentable
- is not finitary algebraic
- is not locally finitely multi-presentable
- is not locally poly-presentable
- is not a generalized variety
- is not multi-algebraic
- is not cartesian closed
- is not complete
- does not have a multi-terminal object
- does not have an initial object
- does not have disjoint coproducts
- is not infinitary distributive
- is not countably distributive
- is not countably extensive
- is not infinitary extensive
- does not have products
- does not have countable products
- does not have ℵ₂-small powers
- does not have finite powers
- does not have connected limits
- is not Barr-exact
- does not have a subobject classifier
- does not have a regular subobject classifier
- is not a Grothendieck topos
- is not a pretopos
- is not total
- is not locally finitely copresentable
- is not finitely coaccessible
- is not locally copresentable
- is not locally multi-copresentable
- is not locally finitely multi-copresentable
- is not dually finitary algebraic
- does not have disjoint finite products
- does not have cofiltered-limit-stable epimorphisms
- is not coextensive
- is not infinitary coextensive
- does not have cosifted limits
- does not have a strict terminal object
- does not have coproducts
- does not have ℵ₂-small coproducts
- does not have ℵ₂-small copowers
- does not have finite copowers
- is not a Grothendieck cotopos
- is not a precotopos
- is not cototal
- is not locally multi-presentable
- is not one-sorted finitary algebraic
- is not multi-complete
- does not have a strict initial object
- does not have ℵ₂-small products
- does not have a conatural numbers object
- is not locally ℵ₁-copresentable
- is not dually one-sorted finitary algebraic
- is not a dual generalized variety
- does not have a multi-initial object
- does not have disjoint products
- is not countably coextensive
- is not multi-cocomplete
*This also uses the deduced satisfied properties.
Unknown properties
—
Special objects
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Special morphisms
- isomorphisms: only the neutral element
- monomorphisms: the elements for
- epimorphisms: the elements for
- regular monomorphisms: the elements for
- regular epimorphisms: the elements for