- with S4 ModalSemantics
The semantics for predication, quantification, and truth-functional operators are the same as .
Modal Operators
For modality, we reuse the crunch function from quantification:
Crunched Value
The crunched value of v is 1 (T) if v is 1, else 0 (F).
Possibility
The value of a possibility sentence ◻A at is the maximum of the crunched values of its operand at each world such that is in .
This is in accord with interpreting the possibility operator in terms of generalized disjunction.
Necessity
The value of a necessity sentence ◻A at is the minimum of the crunched values of its operand at each world such that is in .
This is in accord with interpreting the necessity operator in terms of generalized conjunction.
includes the access relation restrictions on models ofReflexivity
In every model, for each world
, is in the access relation.Transitivity
In every model, for each world
, and each world , for any world such that and are in the access relation, then is in the access relation.Tableaux
system tableaux.
tableaux are constructed just likeNodes
Nodes for many-valued modal tableaux come in two types:
A node consisting of a sentence, a designation marker (⊕ or ⊖), and a world.
An access node like
, indicating that the pair is in the access relation .
Trunk
To build the trunk for an argument, add a designated node with each premise at world
, followed by an undesignated node with the the conclusion at world .Closure
includes theRules
rules, and adds modal operator rules, as well as the access rules.
contains all theModal Operator Rules
◇ Rules
◻ Rules
Access Rules
Operator Rules
⚬ Rules
¬ Rules
∧ Rules
∨ Rules
⊃ Rules
≡ Rules
→ Rules
- →⊕Conditional Designated[source]
- A → B ⊕, w0⋮¬A ∨ B ⊕, w0A ⊖, w0B ⊖, w0¬A ⊖, w0¬B ⊖, w0
↔ Rules
Quantifier Rules
∃ Rules
∀ Rules
Notes
References
Doug Owings (2012). Indeterminacy and Logical Atoms. Ph.D. Thesis, University of Connecticut.