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Material nonimplication or abjunction (Latin ab = "away", junctio= "to join") is a term referring to a logic operation used in generic circuits and Boolean algebra. It is the negation of material implication. That is to say that for any two propositions ${\displaystyle P}$ and ${\displaystyle Q}$, the material nonimplication from ${\displaystyle P}$ to ${\displaystyle Q}$ is true if and only if the negation of the material implication from ${\displaystyle P}$ to ${\displaystyle Q}$ is true. This is more naturally stated as that the material nonimplication from ${\displaystyle P}$ to ${\displaystyle Q}$ is true only if ${\displaystyle P}$ is true and ${\displaystyle Q}$ is false.

It may be written using logical notation as ${\displaystyle P\nrightarrow Q}$, ${\displaystyle P\not \supset Q}$, or "Lpq" (in Bocheński notation), and is logically equivalent to ${\displaystyle \neg (P\rightarrow Q)}$, and ${\displaystyle P\land \neg Q}$.

Definition

Truth table

${\displaystyle A}$	${\displaystyle B}$	${\displaystyle A\nrightarrow B}$
F	F	F
F	T	F
T	F	T
T	T	F

Logical Equivalences

Material nonimplication may be defined as the negation of material implication.

${\displaystyle P\nrightarrow Q}$	${\displaystyle \Leftrightarrow }$	${\displaystyle \neg (P\rightarrow Q)}$
	${\displaystyle \Leftrightarrow }$	${\displaystyle \neg }$

In classical logic, it is also equivalent to the negation of the disjunction of ${\displaystyle \neg P}$ and ${\displaystyle Q}$, and also the conjunction of ${\displaystyle P}$ and ${\displaystyle \neg Q}$

${\displaystyle P\nrightarrow Q}$	${\displaystyle \Leftrightarrow }$	${\displaystyle \neg (}$	${\displaystyle \neg P}$	${\displaystyle \lor }$	${\displaystyle Q)}$	${\displaystyle \Leftrightarrow }$	${\displaystyle P}$	${\displaystyle \land }$	${\displaystyle \neg Q}$
	${\displaystyle \Leftrightarrow }$	${\displaystyle \neg (}$		${\displaystyle \lor }$	${\displaystyle )}$	${\displaystyle \Leftrightarrow }$		${\displaystyle \land }$

Properties

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 material nonimplication.

Symbol

The symbol for material nonimplication is simply a crossed-out material implication symbol. Its Unicode symbol is 219B₁₆ (8603 decimal): ↛.

Natural language

Grammatical

"p minus q."

"p without q."

Rhetorical

"p but not q."

"q is false, in spite of p."

Computer science

Bitwise operation: A&(~B)

Logical operation: A&&(!B)

See also

• Implication
• Set difference

References

1. Berco, Dan; Ang, Diing Shenp; Kalaga, Pranav Sairam (2020). "Programmable Photoelectric Memristor Gates for In Situ Image Compression". Advanced Intelligent Systems. 2 (9): 5. doi:10.1002/aisy.202000079.

External links

• Media related to Material nonimplication at Wikimedia Commons

v t e Common logical connectives
Tautology/True ${\displaystyle \top }$
Alternative denial (NAND gate) ${\displaystyle \uparrow }$ Converse implication ${\displaystyle \leftarrow }$ Implication (IMPLY gate) ${\displaystyle \rightarrow }$ Disjunction (OR gate) ${\displaystyle \lor }$
Negation (NOT gate) ${\displaystyle \neg }$ Exclusive or (XOR gate) ${\displaystyle \not \leftrightarrow }$ Biconditional (XNOR gate) ${\displaystyle \leftrightarrow }$ Statement (Digital buffer)
Joint denial (NOR gate) ${\displaystyle \downarrow }$ Nonimplication (NIMPLY gate) ${\displaystyle \nrightarrow }$ Converse nonimplication ${\displaystyle \nleftarrow }$ Conjunction (AND gate) ${\displaystyle \land }$
Contradiction/False ${\displaystyle \bot }$
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