Category of Profinite Groups #
We say G
is a profinite group if it is a topological group which is compact and totally
disconnected.
Main definitions and results #
ProfiniteGrp
is the category of profinite groups.ProfiniteGrp.pi
: The pi-type of profinite groups is also a profinite group.ofFiniteGrp
: AFiniteGrp
when given the discrete topology can be considered as a profinite group.ofClosedSubgroup
: A closed subgroup of a profinite group is profinite.
The category of profinite groups. A term of this type consists of a profinite set with a topological group structure.
- toProfinite : Profinite
The underlying profinite topological space.
- group : Group ↑self.toProfinite.toTop
The group structure.
- topologicalGroup : IsTopologicalGroup ↑self.toProfinite.toTop
The above data together form a topological group.
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The category of profinite additive groups. A term of this type consists of a profinite set with a topological additive group structure.
- toProfinite : Profinite
The underlying profinite topological space.
- addGroup : AddGroup ↑self.toProfinite.toTop
The additive group structure.
- topologicalAddGroup : IsTopologicalAddGroup ↑self.toProfinite.toTop
The above data together form a topological additive group.
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Construct a term of ProfiniteGrp
from a type endowed with the structure of a
compact and totally disconnected topological group.
(The condition of being Hausdorff can be omitted here because totally disconnected implies that {1}
is a closed set, thus implying Hausdorff in a topological group.)
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Construct a term of ProfiniteAddGrp
from a type endowed with the structure of a
compact and totally disconnected topological additive group.
(The condition of being Hausdorff can be omitted here because totally disconnected implies that {0}
is a closed set, thus implying Hausdorff in a topological additive group.)
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The underlying ContinuousMonoidHom
.
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The underlying ContinuousAddMonoidHom
.
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Typecheck a ContinuousMonoidHom
as a morphism in ProfiniteGrp
.
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Typecheck a ContinuousAddMonoidHom
as a morphism in ProfiniteAddGrp
.
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Construct a term of ProfiniteGrp
from a type endowed with the structure of a
profinite topological group.
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Construct a term of ProfiniteAddGrp
from a type endowed with the structure of a
profinite topological additive group.
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The pi-type of profinite groups is a profinite group.
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The pi-type of profinite additive groups is a profinite additive group.
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A FiniteGrp
when given the discrete topology can be considered as a profinite group.
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A FiniteAddGrp
when given the discrete topology can be considered as a
profinite additive group.
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A closed subgroup of a profinite group is profinite.
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A closed additive subgroup of a profinite additive group is profinite.
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A topological group that has a ContinuousMulEquiv
to a profinite group is profinite.
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A topological additive group that has a ContinuousAddEquiv
to a
profinite additive group is profinite.
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Build an isomorphism in the category ProfiniteGrp
from
a ContinuousMulEquiv
between ProfiniteGrp
s.
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The functor mapping a profinite group to its underlying profinite space.
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Limits in the category of profinite groups #
In this section, we construct limits in the category of profinite groups.
ProfiniteGrp.limitCone
: The explicit limit cone inProfiniteGrp
.ProfiniteGrp.limitConeIsLimit
:ProfiniteGrp.limitCone
is a limit cone.
TODO #
- Figure out the reason that is causing
to_additive
to fail in most part of this section and generate the additive version correctly.
Auxiliary construction to obtain the group structure on the limit of profinite groups.
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Auxiliary construction to obtain the additive group structure on the limit of profinite additive groups.
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The explicit limit cone in ProfiniteGrp
.
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ProfiniteGrp.limitCone
is a limit cone.
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The abbreviation for the limit of ProfiniteGrp
s.