- Weak Kleene Logic with alternate quantificationThis is a version of 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 .
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
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:
Likewise the Material Biconditional ≡ is defined in terms of ⊃ and ∧:
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
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 has the value:
T iff \(P\) and not in the anti-extension of \(P\).
is in the extension ofF iff \(P\) and not in the extension of \(P\).
is in the anti-extension ofN iff \(P\).
is in neither the extension nor the anti-extension of
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
tableaux are built similary to .
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.
Closure
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
∧ Rules
∨ Rules
⊃ Rules
≡ Rules
Quantifier Rules
∃ Rules
∀ Rules
Compatibility Rules
⚬ Rules
→ Rules
↔ Rules
Notes
Standard interdefinability of the quantifiers is preserved.