S4GO - GO with S4 Modal


Semantics

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

Tableaux

S4GO tableaux are constructed just like KFDE system 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 ... AnB write:
A1 , w0
An , w0
B , w0

Closure

S4GO includes the K3 and FDE closure rules.

K3Glut Closure[source]
A , w0
¬A , w0
FDEDesignation Closure[source]
A , w0
A , w0

Rules

S4GO contains all the GO rules, and adds modal operator rules, as well as the S4 access rules.

Access Rules

R+S4Transitive[source]
w0Rw1
w1Rw2
w0Rw2
R≤TReflexive[source]
A, w0
w0Rw0

Operator Rules

⚬ Rules
FDEAssertion Designated[source]
⚬A , w0
A , w0
FDEAssertion Undesignated[source]
⚬A , w0
A , w0
¬B3EAssertion Negated Designated[source]
¬⚬A , w0
A , w0
¬B3EAssertion Negated Undesignated[source]
¬⚬A , w0
A , w0
¬ Rules
¬¬FDEDouble Negation Designated[source]
¬¬A , w0
A , w0
¬¬FDEDouble Negation Undesignated[source]
¬¬A , w0
A , w0
∧ Rules
FDEConjunction Designated[source]
A ∧ B , w0
A , w0
B , w0
GOConjunction Undesignated[source]
A ∧ B , w0
¬(A ∧ B) , w0
¬GOConjunction Negated Designated[source]
¬(A ∧ B) , w0
A , w0
B , w0
¬GOConjunction Negated Undesignated[source]
¬(A ∧ B) , w0
A ∧ B , w0
∨ Rules
FDEDisjunction Designated[source]
A ∨ B , w0
A , w0
B , w0
GODisjunction Undesignated[source]
A ∨ B , w0
¬(A ∨ B) , w0
¬GODisjunction Negated Designated[source]
¬(A ∨ B) , w0
A , w0
B , w0
¬GODisjunction Negated Undesignated[source]
¬(A ∨ B) , w0
A ∨ B , w0
⊃ Rules
FDEMaterial Conditional Designated[source]
A ⊃ B , w0
¬A , w0
B , w0
GOMaterial Conditional Undesignated[source]
A ⊃ B , w0
¬(A ⊃ B) , w0
¬GOMaterial Conditional Negated Designated[source]
¬(A ⊃ B) , w0
¬A , w0
B , w0
¬GOMaterial Conditional Negated Undesignated[source]
¬(A ⊃ B) , w0
A ⊃ B , w0
≡ Rules
FDEMaterial Biconditional Designated[source]
A ≡ B , w0
¬A , w0
¬B , w0
B , w0
A , w0
GOMaterial Biconditional Undesignated[source]
A ≡ B , w0
¬(A ≡ B) , w0
¬GOMaterial Biconditional Negated Designated[source]
¬(A ≡ B) , w0
¬A , w0
B , w0
A , w0
¬B , w0
¬GOMaterial Biconditional Negated Undesignated[source]
¬(A ≡ B) , w0
A ≡ B , w0
→ Rules
L3Conditional Designated[source]
A → B , w0
¬A ∨ B , w0
A , w0
B , w0
¬A , w0
¬B , w0
GOConditional Undesignated[source]
A → B , w0
¬(A → B) , w0
¬GOConditional Negated Designated[source]
¬(A → B) , w0
A , w0
B , w0
¬A , w0
¬B , w0
¬GOConditional Negated Undesignated[source]
¬(A → B) , w0
A → B , w0
↔ Rules
GOBiconditional Designated[source]
A ↔ B , w0
A → B , w0
B → A , w0
GOBiconditional Undesignated[source]
A ↔ B , w0
¬(A ↔ B) , w0
¬GOBiconditional Negated Designated[source]
¬(A ↔ B) , w0
¬(A → B) , w0
¬(B → A) , w0
¬GOBiconditional Negated Undesignated[source]
¬(A ↔ B) , w0
A ↔ B , w0

Quantifier Rules

∃ Rules
FDEExistential Designated[source]
∃xFx , w0
Fa , w0
GOExistential Undesignated[source]
∃xFx , w0
¬∃xFx , w0
¬GOExistential Negated Designated[source]
¬∃xFx , w0
∀x(¬Fx ∨ ¬(Fx ∨ ¬Fx)) , w0
¬GOExistential Negated Undesignated[source]
¬∃xFx , w0
∃xFx , w0
∀ Rules
FDEUniversal Designated[source]
∀xFx , w0
Fa , w0
GOUniversal Undesignated[source]
∀xFx , w0
¬∀xFx , w0
¬GOUniversal Negated Designated[source]
¬∀xFx , w0
∃x¬Fx , w0
Fa , w0
¬Fa , w0
¬GOUniversal Negated Undesignated[source]
¬∀xFx , w0
∀xFx , w0

Notes

References