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Exemplaric Expressivityof Modal Logics
Ana Sokolova University of Salzburg
joint work with
Bart Jacobs Radboud University Nijmegen
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 2
It is about... Coalgebras
Modal logics
Behaviour
functor !
In a studied setting of
dual adjunctions
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 3
Outline Expressivity:
logical equivalence = behavioral equivalence
For four examples:
1. Transition systems2. Markov chains3. Multitransition systems4. Markov processes
Boolean modal logic
Finite conjunctions „valuation“ modal logic
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 4
Via dual adjunctionsPredicates on
spaces
Theories on
modelsBehaviour
(coalgebras) Logics(algebras)
Dual
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 5
Logical set-up
If L has an initial algebra of formulas
A natural transformation
gives interpretations
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 6
Logical equivalencebehavioural equivalence
The interpretation map yields a theory map
which defines logical equivalence
behavioural equivalence is given by for some coalgebra
homomorphismsh1 and h2
Aim: expressivity
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 7
Expressivity Bijective correspondence between
and
If and the transpose of the interpretation
is componentwise abstract mono, then expressivity.
Factorisation system on
with diagonal fill-in
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 8
Sets vs. Boolean algebras contravariant
powerset
Boolean algebra
s
ultrafilters
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 9
Sets vs. meet semilattices
meet semilattice
s
contravariant powerset
filters
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 10
Measure spaces vs. meet semilattices
measure spaces
¾-algebra: “measurable
”subsets
closed under empty,
complement, countable
union
maps a measure space to its ¾-algebra
filters on A with ¾-algebra generated
by
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 11
Behaviour via coalgebras Transition systems
Markov chains/Multitransition systems
Markov processes
Giry monad
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What do they have in common?They are instances of the same functor
Not cancellativ
e
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The Giry monad
subprobability measures
countable union of pairwise disjoint
generated by
the smallest making
measurable
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Logic for transition systems
Modal operator
models of boolean
logic with fin.meet
preserving modal
operators
L = GVV - forgetful
expressivity
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 15
Logic for Markov chains Probabilistic modalities
models of logic with fin.conj.
andmonotone
modal operators
K = HVV - forgetful
expressivity
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 16
Logic for multitransition ... Graded modal logic modalities
models of logic with fin.conj.
andmonotone
modal operators
K = HVV - forgetful
expressivity
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 17
Logic for Markov processes
General probabilistic modalities
models of logic with fin.conj.
andmonotone
modal operators
the same K
expressivity
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 18
Discrete to indiscrete The adjunctions are related:
discrete measure
space
forgetfulfunctor
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Discrete to indiscrete Markov chains as Markov processes
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Discrete to indiscrete So we can translate chains into
processes
Behavioural equivalence
coincides
Also the logic
theories do
Dagstuhl Seminar on Coalgebraic Logics, 7.12.9 21
Or directly ...
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Conclusions Expressivity
For four examples:
1. Transition systems2. Multitransition systems3. Markov chains4. Markov processes
Boolean modal logic
Finite conjunctions ``valuation´´ modal logic
in the setting of dual adjunctions !