Logical Connectives

In logic, a logical connective (also called a logical operator, sentential connective, or sentential operator) is a logical constant used to connect two or more formulas. For instance in the syntax of propositional logic, the binary connective {\displaystyle \lor }\lor can be used to join the two atomic formulas {\displaystyle P} P and {\displaystyle Q} Q, rendering the complex formula {\displaystyle P\lor Q}P\lor Q.

Common connectives include negation, disjunction, conjunction, and implication. In standard systems of classical logic, these connectives are interpreted as truth functions, though they receive a variety of alternative interpretations in nonclassical logics. Their classical interpretations are similar to the meanings of natural language expressions such as English not, or, and, and if, but not identical. Discrepancies between natural language connectives and those of classical logic have motivated nonclassical approaches to natural language meaning as well as approaches which pair a classical compositional semantics with a robust pragmatics.

English word mantrakshar Connective Venn Diagram Symbol Logical gate
not Negation ¬ NOT
and Conjunction AND
not both Alternative denial NAND
or Disjunction OR
neither…nor Joint denial NOR
if…then Material implication IMPLY
one or the other but not both Exclusive or XOR
if and only if Biconditional XNOR
…if Converse implication
but not material nonimplication NIMPLY
left is less than right left < right
left is more than right left > right
right is less than left right < left
right is more than left right > left
EXAMPLE IDEOGRAM
truth / tautology box
falsify / contradiction not box
proposition P left
Negation not left
Proposition P and Q
proposition P true left is true
proposition Q True right is true
propositon p and q Conjunction left and right is true , only if left is true and right is true , otherwise it is false AND
Alternative denial not left and not right is the correct output , if either left or right are not correct NAND (not and )
left or right is correct output , if left is correct input or right is correct input

LOGIC GATES

AND ( CONJUNCTION )

left (P) Right (Q)
TRUE TRUE TRUE
TRUE FALSE FALSE
FALSE TRUE FALSE
FALSE FALSE FALSE

NAND ( ALTERNATIVE DENIAL )

left (P) Right (Q)
TRUE TRUE FALSE
TRUE FALSE TRUE
FALSE TRUE TRUE
FALSE FALSE TRUE

OR ( DISJUNCTION )

left (P) Right (Q)
TRUE TRUE TRUE
TRUE FALSE TRUE
FALSE TRUE TRUE
FALSE FALSE FALSE

NOR (JOINT DENIAL )

left (P) Right (Q)
TRUE TRUE FALSE
TRUE FALSE FALSE
FALSE TRUE FALSE
FALSE FALSE TRUE

Material conditional

left (P) Right (Q)
TRUE TRUE TRUE
TRUE FALSE FALSE
FALSE TRUE TRUE
FALSE FALSE TRUE

XOR

left (P) Right (Q)
FALSE FALSE FALSE
FALSE TRUE TRUE
TRUE FALSE TRUE
TRUE TRUE FALSE

Material biconditional

left (P) Right (Q)
TRUE TRUE TRUE
TRUE FALSE FALSE
FALSE TRUE FALSE
FALSE FALSE TRUE

Converse implication

left (P) Right (Q) NAND
TRUE TRUE FALSE
TRUE FALSE FALSE
FALSE TRUE TRUE
FALSE FALSE TRUE