exemplaric expressivity of modal logics
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Exemplaric Expressivityof Modal Logics
Ana Sokolova University of Salzburg
joint work with
Bart Jacobs Radboud University Nijmegen
Coalgebra Day, 11-3-2008, RUN
Coalgebra Day, 11-3-2008, RUN 2
Outline Expressivity:
logical equivalence = behavioral equivalence
For three examples:
1. Transition systems2. Markov chains3. Markov processes
Boolean modal logic
Finite conjunctions probabilistic modal logic
Coalgebra Day, 11-3-2008, RUN 3
Via dual adjunctionsPredicates on
spaces
Theories on
modelsBehaviour
(coalgebras) Logics(algebras)
Dual
Coalgebra Day, 11-3-2008, RUN 4
Logical set-up
If L has an initial algebra of formulas
A natural transformation
gives interpretations
Coalgebra Day, 11-3-2008, RUN 5
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
Coalgebra Day, 11-3-2008, RUN 6
Expressivity Bijective correspondence between
and
If and the transpose of the interpretation
is componentwise mono, then expressivity.Factorisation system on
with diagonal fill-in
Coalgebra Day, 11-3-2008, RUN 7
Sets vs. Boolean algebras contravariant
powerset
Boolean algebra
s
ultrafilters
Coalgebra Day, 11-3-2008, RUN 8
Sets vs. meet semilattices
meet semilattice
s
contravariant powerset
filters
Coalgebra Day, 11-3-2008, RUN 9
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
Coalgebra Day, 11-3-2008, RUN 10
Behaviour via coalgebras Transition systems
Markov chains
Markov processes
Giry monad
Coalgebra Day, 11-3-2008, RUN 11
The Giry monad
subprobability measures
countable union of pairwise disjoint
generated by
the smallest making
measurable
Coalgebra Day, 11-3-2008, RUN 12
Logic for transition systems
Modal operator
models of boolean
logic with fin.meet
preserving modal
operators
L = GVV - forgetful
expressivity
Coalgebra Day, 11-3-2008, RUN 13
Logic for Markov chains Probabilistic modalities
models of logic with fin.conj.
andmonotone
modal operators
K = HVV - forgetful
expressivity
Coalgebra Day, 11-3-2008, RUN 14
Logic for Markov processes
General probabilistic modalities
models of logic with fin.conj.
andmonotone
modal operators
the same K
expressivity
Coalgebra Day, 11-3-2008, RUN 15
Discrete to indescrete The adjunctions are related:
discrete measure
space
forgetfulfunctor
Coalgebra Day, 11-3-2008, RUN 16
Discrete to indiscrete Markov chains as Markov processes
Coalgebra Day, 11-3-2008, RUN 17
Discrete to indiscrete
Coalgebra Day, 11-3-2008, RUN 18
Conclusions Expressivity
For three examples:
1. Transition systems2. Markov chains3. Markov processes
Boolean modal logic
Finite conjunctions probabilistic modal logic
in the setting of dual adjunctions !
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