Converse nonimplication


In logic, converse nonimplication is a logical connective which is the negation of converse implication.

Definition

Converse nonimplication is notated, or, and is logically equivalent to

Truth table

The truth table of.
TTF
TFF
FTT
FFF

Notation

Converse nonimplication is notated, which is the left arrow from converse implication, negated with a stroke.
Alternatives include
falsehood-preserving: The interpretation under which all variables are assigned a truth value of 'false' produces a truth value of 'false' as a result of converse nonimplication

Natural language

Grammatical

"p from q."
Classic passive aggressive: "yeah, no"

Rhetorical

"not A but B"

Colloquial

Boolean algebra


Converse Nonimplication in a general Boolean algebra is defined as.

Example of a 2-element Boolean algebra: the 2 elements with 0 as zero and 1 as unity element, operators as complement operator, as join operator and as meet operator, build the Boolean algebra of propositional logic.



Example of a 4-element Boolean algebra: the 4 divisors of 6 with 1 as zero and 6 as unity element, operators as complement operator, as join operator and as meet operator, build a Boolean algebra.

Properties

Non-associative

iff [|#s5]. Hence in a nontrivial Boolean algebra Converse Nonimplication is nonassociative.
Clearly, it is associative iff.

Non-commutative





Computer science

An example for converse nonimplication in computer science can be found when performing a right outer join on a set of tables from a database, if records not matching the join-condition from the "left" table are being excluded.
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