Filtration for transitive axioms 4
is proposed in KopnevΒ (2023)K. Kopnev,Β 2023. βThe Finite Model Property of Some Non-normal Modal Logics with the Transitivity Axiomβ. arXiv:2305.08605. For this purpose, we need basis filtration, transitiveFiltration
.
πdefLO.Modal.Neighborhood.transitiveFiltration (M : Model) [M.IsTransitive]
(T : FormulaSet β) [T.IsSubformulaClosed] : Filtration M T
LO.Modal.Neighborhood.transitiveFiltration
(M : Model) [M.IsTransitive]
(T : FormulaSet β)
[T.IsSubformulaClosed] : Filtration M T
As the name suggests, transitiveFiltration
is transitive.
πtheoremLO.Modal.Neighborhood.transitiveFiltration.isTransitive {M : Model}
{T : FormulaSet β} [T.IsSubformulaClosed] [M.IsTransitive] :
(transitiveFiltration M T).toModel.IsTransitive LO.Modal.Neighborhood.transitiveFiltration.isTransitive
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed]
[M.IsTransitive] :
(transitiveFiltration M
T).toModel.IsTransitive
Reflexivity is preserved when original model is reflexive.
πtheoremLO.Modal.Neighborhood.transitiveFiltration.isReflexive {M : Model}
{T : FormulaSet β} [T.IsSubformulaClosed] [M.IsTransitive]
[M.IsReflexive] : (transitiveFiltration M T).toModel.IsReflexive LO.Modal.Neighborhood.transitiveFiltration.isReflexive
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed] [M.IsTransitive]
[M.IsReflexive] :
(transitiveFiltration M
T).toModel.IsReflexive
To show that contains-unit property is preserved is not trivial, it needs that β‘β€
is in the filter.
πtheoremLO.Modal.Neighborhood.transitiveFiltration.containsUnit {M : Model}
{T : FormulaSet β} [T.IsSubformulaClosed] [M.IsTransitive]
[M.ContainsUnit] (hT : β‘β€ β T) :
(transitiveFiltration M T).toModel.ContainsUnit LO.Modal.Neighborhood.transitiveFiltration.containsUnit
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed] [M.IsTransitive]
[M.ContainsUnit] (hT : β‘β€ β T) :
(transitiveFiltration M
T).toModel.ContainsUnit
We expand transitiveFiltration
to suites for several logics. First one is for monotonicity, we add supplementation for transitiveFiltration
.
πdefLO.Modal.Neighborhood.supplementedTransitiveFiltration (M : Model)
[M.IsMonotonic] [M.IsTransitive] (T : FormulaSet β)
[T.IsSubformulaClosed] : Filtration M T
LO.Modal.Neighborhood.supplementedTransitiveFiltration
(M : Model) [M.IsMonotonic]
[M.IsTransitive] (T : FormulaSet β)
[T.IsSubformulaClosed] : Filtration M T
By supplementation, monotonicity is recovered.
πtheoremLO.Modal.Neighborhood.supplementedTransitiveFiltration.isMonotonic
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] :
(supplementedTransitiveFiltration M T).toModel.IsMonotonic LO.Modal.Neighborhood.supplementedTransitiveFiltration.isMonotonic
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] :
(supplementedTransitiveFiltration M
T).toModel.IsMonotonic
Similarly, transitivity, reflexivity and contains-unit property is preserved (of course contains-unit needs β‘β€
is in filter).
πtheoremLO.Modal.Neighborhood.supplementedTransitiveFiltration.isTransitive
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] :
(supplementedTransitiveFiltration M T).toModel.IsTransitive LO.Modal.Neighborhood.supplementedTransitiveFiltration.isTransitive
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] :
(supplementedTransitiveFiltration M
T).toModel.IsTransitive
πtheoremLO.Modal.Neighborhood.supplementedTransitiveFiltration.isReflexive
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] [M.IsReflexive] :
(supplementedTransitiveFiltration M T).toModel.IsReflexive LO.Modal.Neighborhood.supplementedTransitiveFiltration.isReflexive
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] [M.IsReflexive] :
(supplementedTransitiveFiltration M
T).toModel.IsReflexive
πtheoremLO.Modal.Neighborhood.supplementedTransitiveFiltration.containsUnit
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] [M.ContainsUnit] (hT : β‘β€ β T) :
(supplementedTransitiveFiltration M T).toModel.ContainsUnit LO.Modal.Neighborhood.supplementedTransitiveFiltration.containsUnit
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed] [M.IsMonotonic]
[M.IsTransitive] [M.ContainsUnit]
(hT : β‘β€ β T) :
(supplementedTransitiveFiltration M
T).toModel.ContainsUnit
Second one is for regularity, we add quasi-filtering for transitiveFiltration
.
πdefLO.Modal.Neighborhood.quasiFilteringTransitiveFiltration (M : Model)
[M.IsMonotonic] [M.IsTransitive] [M.IsRegular] (T : FormulaSet β)
[T.IsSubformulaClosed] (hT : Set.Finite T) : Filtration M T
LO.Modal.Neighborhood.quasiFilteringTransitiveFiltration
(M : Model) [M.IsMonotonic]
[M.IsTransitive] [M.IsRegular]
(T : FormulaSet β)
[T.IsSubformulaClosed]
(hT : Set.Finite T) : Filtration M T
By quasi-filtering, regularity is recovered.
πtheoremLO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.isRegular
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed]
{T_finite : Set.Finite T} [M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] :
(quasiFilteringTransitiveFiltration M T T_finite).toModel.IsRegular LO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.isRegular
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed]
{T_finite : Set.Finite T}
[M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] :
(quasiFilteringTransitiveFiltration M T
T_finite).toModel.IsRegular
Similarly, Transitivity and reflexivity are preserved, and contains-unit property is preserved.
πtheoremLO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.isMonotonic
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed]
{T_finite : Set.Finite T} [M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] :
(quasiFilteringTransitiveFiltration M T T_finite).toModel.IsMonotonic LO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.isMonotonic
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed]
{T_finite : Set.Finite T}
[M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] :
(quasiFilteringTransitiveFiltration M T
T_finite).toModel.IsMonotonic
πtheoremLO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.isTransitive
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed]
{T_finite : Set.Finite T} [M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] :
(quasiFilteringTransitiveFiltration M T T_finite).toModel.IsTransitive LO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.isTransitive
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed]
{T_finite : Set.Finite T}
[M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] :
(quasiFilteringTransitiveFiltration M T
T_finite).toModel.IsTransitive
πtheoremLO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.containsUnit
{M : Model} {T : FormulaSet β} [T.IsSubformulaClosed]
{T_finite : Set.Finite T} [M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] [M.ContainsUnit] (hT : β‘β€ β T) :
(quasiFilteringTransitiveFiltration M T T_finite).toModel.ContainsUnit LO.Modal.Neighborhood.quasiFilteringTransitiveFiltration.containsUnit
{M : Model} {T : FormulaSet β}
[T.IsSubformulaClosed]
{T_finite : Set.Finite T}
[M.IsMonotonic] [M.IsTransitive]
[M.IsRegular] [M.ContainsUnit]
(hT : β‘β€ β T) :
(quasiFilteringTransitiveFiltration M T
T_finite).toModel.ContainsUnit