K3WQ - Weak Kleene Logic with alternate quantification

This is a version of K3W with a different treatment of the quantifiers in terms of generalized conjunction/disjunction. This yields some interesting rules for the quantifiers, given the behavior of those operators in K3W.


Semantics

Truth Values

Common labels for the values include:

T

1

true

N

0.5

meaningless

F

0

false

Designated Values

The set of designated values for K3WQ is the singleton: { T }

Truth Tables

The value of a sentence with a truth-functional operator is determined by the values of its operands according to the following tables.

Negation
¬
T F
N N
F T
Conjunction
T N F
T T N F
N N N N
F F N F
Disjunction
T N F
T T N T
N N N N
F T N F

Defined Operators

The Material Conditional is definable in terms of disjunction:

A ⊃ B \(:=\) ¬A ∨ B

Likewise the Material Biconditional is defined in terms of and :

A ≡ B \(:=\) (A ⊃ B) ∧ (B ⊃ A)
Material Conditional
T N F
T T N F
N N N N
F T N T
Material Biconditional
T N F
T T N F
N N N N
F F N T

Compatibility Tables

K3WQ does not have separate Assertion or Conditional operators, but we include tables and rules for them, for cross-compatibility.

Assertion
T T
N N
F F
Conditional
T N F
T T N F
N N N N
F T N T
Biconditional
T N F
T T N F
N N N N
F F N T

Predication

A sentence with n-ary predicate \(P\) over parameters \(\langle a_0, ... ,a_n\rangle\) has the value:

  • T iff \(\langle a_0, ... ,a_n\rangle\) is in the extension of \(P\) and not in the anti-extension of \(P\).

  • F iff \(\langle a_0, ... ,a_n\rangle\) is in the anti-extension of \(P\) and not in the extension of \(P\).

  • N iff \(\langle a_0, ... ,a_n\rangle\) is in neither the extension nor the anti-extension of \(P\).

Quantification

Existential

An existential sentence is interpreted in terms of generalized disjunction. If we order the values least to greatest as N, T, F, then we can define the value of an existential in terms of the maximum value of the set of values for the substitution of each constant in the model for the variable.

Universal

A universal sentence is interpreted in terms of generalized conjunction. If we order the values least to greatest as N, F, T, then we can define the value of a universal in terms of the minimum value of the set of values for the substitution of each constant in the model for the variable.

Consequence

Logical Consequence is defined in terms of the set of designated values { T }:

Logical Consequence

C is a Logical Consequence of A iff all models where A has a desginated value are models where C also has a designated value.

Tableaux

K3WQ tableaux are built similary to FDE.

Nodes

Nodes for many-value tableaux consiste of a sentence plus a designation marker: ⊕ for designated, and ⊖ for undesignated.

Trunk

To build the trunk for an argument, add a designated node for each premise, and an undesignated node for the conclusion.

To build the trunk for the argument A1 ... AnB write:
A1
An
B

Closure

Glut Closure[source]
A
¬A
Designation Closure[source]
A
A

Rules

In general, rules for connectives consist of four rules per connective: a designated rule, an undesignated rule, a negated designated rule, and a negated undesignated rule. The special case of negation has a total of two rules which apply to double negation only, one designated rule, and one undesignated rule.

Operator Rules

¬ Rules
¬¬FDEDouble Negation Designated[source]
¬¬A
A
¬¬FDEDouble Negation Undesignated[source]
¬¬A
A
∧ Rules
FDEConjunction Designated[source]
A ∧ B
A
B
FDEConjunction Undesignated[source]
A ∧ B
A
B
¬K3WConjunction Negated Designated[source]
¬(A ∧ B)
A
¬B
¬A
B
¬A
¬B
¬K3WConjunction Negated Undesignated[source]
¬(A ∧ B)
A
¬A
B
¬B
A
B
∨ Rules
K3WDisjunction Designated[source]
A ∨ B
A
¬B
¬A
B
A
B
K3WDisjunction Undesignated[source]
A ∨ B
A
¬A
B
¬B
¬A
¬B
¬FDEDisjunction Negated Designated[source]
¬(A ∨ B)
¬A
¬B
¬K3WDisjunction Negated Undesignated[source]
¬(A ∨ B)
A ∨ B
A
¬A
B
¬B
⊃ Rules
K3WMaterial Conditional Designated[source]
A ⊃ B
¬A ∨ B
K3WMaterial Conditional Undesignated[source]
A ⊃ B
¬A ∨ B
¬K3WMaterial Conditional Negated Designated[source]
¬(A ⊃ B)
¬(¬A ∨ B)
¬K3WMaterial Conditional Negated Undesignated[source]
¬(A ⊃ B)
¬(¬A ∨ B)
≡ Rules
K3WMaterial Biconditional Designated[source]
A ≡ B
(A ⊃ B) ∧ (B ⊃ A)
K3WMaterial Biconditional Undesignated[source]
A ≡ B
(A ⊃ B) ∧ (B ⊃ A)
¬K3WMaterial Biconditional Negated Designated[source]
¬(A ≡ B)
¬((A ⊃ B) ∧ (B ⊃ A))
¬K3WMaterial Biconditional Negated Undesignated[source]
¬(A ≡ B)
¬((A ⊃ B) ∧ (B ⊃ A))

Quantifier Rules

∃ Rules
Existential Designated[source]
∃xFx
∀x(Fx ∨ ¬Fx)
Fa
Existential Undesignated[source]
∃xFx
Fa
¬Fa
∀x¬Fx
¬FDEExistential Negated Designated[source]
¬∃xFx
∀x¬Fx
¬Existential Negated Undesignated[source]
¬∃xFx
¬Fa
∀ Rules
FDEUniversal Designated[source]
∀xFx
Fa
FDEUniversal Undesignated[source]
∀xFx
Fa
¬Universal Negated Designated[source]
¬∀xFx
∀x(Fx ∨ ¬Fx)
¬Fa
¬Universal Negated Undesignated[source]
¬∀xFx
Fa
¬Fa
∀xFx

Compatibility Rules

⚬ Rules
FDEAssertion Designated[source]
⚬A
A
FDEAssertion Undesignated[source]
⚬A
A
¬FDEAssertion Negated Designated[source]
¬⚬A
¬A
¬FDEAssertion Negated Undesignated[source]
¬⚬A
¬A
→ Rules
K3WConditional Designated[source]
A → B
¬A ∨ B
K3WConditional Undesignated[source]
A → B
¬A ∨ B
¬K3WConditional Negated Designated[source]
¬(A → B)
¬(¬A ∨ B)
¬K3WConditional Negated Undesignated[source]
¬(A → B)
¬(¬A ∨ B)
↔ Rules
K3WBiconditional Designated[source]
A ↔ B
(A ⊃ B) ∧ (B ⊃ A)
K3WBiconditional Undesignated[source]
A ↔ B
(A ⊃ B) ∧ (B ⊃ A)
¬K3WBiconditional Negated Designated[source]
¬(A ↔ B)
¬((A ⊃ B) ∧ (B ⊃ A))
¬K3WBiconditional Negated Undesignated[source]
¬(A ↔ B)
¬((A ⊃ B) ∧ (B ⊃ A))

Notes

  • Standard interdefinability of the quantifiers is preserved.

References