KG3 - G3 with K Modal


Semantics

A KG3 frame comprises the interpretation of sentences and predicates at a world. A KG3 model comprises a non-empty collection of KG3 frames, a world access relation \(R\), and a set of constants (the domain).

The semantics for predication, quantification, and truth-functional operators are the same as G3.

Consequence

Logical Consequence is defined just as in KFDE.

Logical Consequence

C is a Logical Consequence of A iff all models where A has a desginated value at \(w_0\) are models where C also has a designated value at \(w_0\).

Tableaux

Nodes

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 \(w_1Rw_2\), indicating that the pair \(\langle\ w_1, w_2\ \rangle\) is in the access relation \(R\).

Trunk

To build the trunk for an argument, add a designated node with each premise at world \(w_0\), followed by an undesignated node with the the conclusion at world \(w_0\).

To build the trunk for the argument A1 ... An ∴ B write:
A1 ⊕, w0
⋮
An ⊕, w0
B ⊖, w0

Closure

The closure rules are the same as G3.

⊗K3Glut Closure[source]
A ⊕, w0
⋮
¬A ⊕, w0
⊗
⊗FDEDesignation Closure[source]
A ⊕, w0
⋮
A ⊖, w0
⊗

Rules

Non-modal rules for KG3 are exactly like their G3 counterparts, with the addition of carrying over the world marker from the target node(s).

Operator Rules

¬ Rules
¬¬⊕G3Double Negation Designated[source]
¬¬A ⊕, w0
⋮
¬A ⊖, w0
¬¬⊖G3Double Negation Undesignated[source]
¬¬A ⊖, w0
⋮
¬A ⊕, w0
∧ Rules
∧⊕FDEConjunction Designated[source]
A ∧ B ⊕, w0
⋮
A ⊕, w0
B ⊕, w0
∧⊖FDEConjunction Undesignated[source]
A ∧ B ⊖, w0
⋮
A ⊖, w0
B ⊖, w0
¬∧⊕FDEConjunction Negated Designated[source]
¬(A ∧ B) ⊕, w0
⋮
¬A ⊕, w0
¬B ⊕, w0
¬∧⊖FDEConjunction Negated Undesignated[source]
¬(A ∧ B) ⊖, w0
⋮
¬A ⊖, w0
¬B ⊖, w0
∨ Rules
∨⊕FDEDisjunction Designated[source]
A ∨ B ⊕, w0
⋮
A ⊕, w0
B ⊕, w0
∨⊖FDEDisjunction Undesignated[source]
A ∨ B ⊖, w0
⋮
A ⊖, w0
B ⊖, w0
¬∨⊕FDEDisjunction Negated Designated[source]
¬(A ∨ B) ⊕, w0
⋮
¬A ⊕, w0
¬B ⊕, w0
¬∨⊖FDEDisjunction Negated Undesignated[source]
¬(A ∨ B) ⊖, w0
⋮
¬A ⊖, w0
¬B ⊖, w0
⊃ Rules
⊃⊕G3Material Conditional Designated[source]
A ⊃ B ⊕, w0
⋮
¬A ∨ B ⊕, w0
⊃⊖G3Material Conditional Undesignated[source]
A ⊃ B ⊖, w0
⋮
¬A ∨ B ⊖, w0
¬⊃⊕G3Material Conditional Negated Designated[source]
¬(A ⊃ B) ⊕, w0
⋮
¬(¬A ∨ B) ⊕, w0
¬⊃⊖G3Material Conditional Negated Undesignated[source]
¬(A ⊃ B) ⊖, w0
⋮
¬(¬A ∨ B) ⊖, w0
≡ Rules
≡⊕G3Material Biconditional Designated[source]
A ≡ B ⊕, w0
⋮
(A ⊃ B) ∧ (B ⊃ A) ⊕, w0
≡⊖G3Material Biconditional Undesignated[source]
A ≡ B ⊖, w0
⋮
(A ⊃ B) ∧ (B ⊃ A) ⊖, w0
¬≡⊕G3Material Biconditional Negated Designated[source]
¬(A ≡ B) ⊕, w0
⋮
¬((A ⊃ B) ∧ (B ⊃ A)) ⊕, w0
¬≡⊖G3Material Biconditional Negated Undesignated[source]
¬(A ≡ B) ⊖, w0
⋮
¬((A ⊃ B) ∧ (B ⊃ A)) ⊖, w0
→ Rules
→⊕L3Conditional Designated[source]
A → B ⊕, w0
⋮
¬A ∨ B ⊕, w0
A ⊖, w0
B ⊖, w0
¬A ⊖, w0
¬B ⊖, w0
→⊖L3Conditional Undesignated[source]
A → B ⊖, w0
⋮
A ⊕, w0
B ⊖, w0
A ⊖, w0
¬A ⊖, w0
¬B ⊕, w0
¬→⊕G3Conditional Negated Designated[source]
¬(A → B) ⊕, w0
⋮
A ⊕, w0
¬B ⊕, w0
A ⊖, w0
¬A ⊖, w0
¬B ⊕, w0
¬→⊖G3Conditional Negated Undesignated[source]
¬(A → B) ⊖, w0
⋮
¬A ⊕, w0
¬B ⊖, w0
↔ Rules
↔⊕G3Biconditional Designated[source]
A ↔ B ⊕, w0
⋮
(A → B) ∧ (B → A) ⊕, w0
↔⊖G3Biconditional Undesignated[source]
A ↔ B ⊖, w0
⋮
(A → B) ∧ (B → A) ⊖, w0
¬↔⊕G3Biconditional Negated Designated[source]
¬(A ↔ B) ⊕, w0
⋮
¬((A → B) ∧ (B → A)) ⊕, w0
¬↔⊖G3Biconditional Negated Undesignated[source]
¬(A ↔ B) ⊖, w0
⋮
¬((A → B) ∧ (B → A)) ⊖, w0

Quantifier Rules

∃ Rules
∃⊕FDEExistential Designated[source]
∃xFx ⊕, w0
⋮
Fa ⊕, w0
∃⊖FDEExistential Undesignated[source]
∃xFx ⊖, w0
⋮
Fa ⊖, w0
¬∃⊕FDEExistential Negated Designated[source]
¬∃xFx ⊕, w0
⋮
∀x¬Fx ⊕, w0
¬∃⊖FDEExistential Negated Undesignated[source]
¬∃xFx ⊖, w0
⋮
∀x¬Fx ⊖, w0
∀ Rules
∀⊕FDEUniversal Designated[source]
∀xFx ⊕, w0
⋮
Fa ⊕, w0
∀⊖FDEUniversal Undesignated[source]
∀xFx ⊖, w0
⋮
Fa ⊖, w0
¬∀⊕FDEUniversal Negated Designated[source]
¬∀xFx ⊕, w0
⋮
∃x¬Fx ⊕, w0
¬∀⊖FDEUniversal Negated Undesignated[source]
¬∀xFx ⊖, w0
⋮
∃x¬Fx ⊖, w0

Compatibility Rules

⚬ Rules
⚬⊕FDEAssertion Designated[source]
⚬A ⊕, w0
⋮
A ⊕, w0
⚬⊖FDEAssertion Undesignated[source]
⚬A ⊖, w0
⋮
A ⊖, w0
¬⚬⊕FDEAssertion Negated Designated[source]
¬⚬A ⊕, w0
⋮
¬A ⊕, w0
¬⚬⊖FDEAssertion Negated Undesignated[source]
¬⚬A ⊖, w0
⋮
¬A ⊖, w0

Notes

References