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  2. List of logic symbols - Wikipedia

    en.wikipedia.org/wiki/List_of_logic_symbols

    negation: not propositional logic, Boolean algebra: The statement is true if and only if A is false. A slash placed through another operator is the same as placed in front. The prime symbol is placed after the negated thing, e.g. ′ [2]

  3. Material implication (rule of inference) - Wikipedia

    en.wikipedia.org/wiki/Material_implication_(rule...

    An example: we are given the conditional fact that if it is a bear, then it can swim. Then, all 4 possibilities in the truth table are compared to that fact. If it is a bear, then it can swim — T; If it is a bear, then it can not swim — F; If it is not a bear, then it can swim — T because it doesn’t contradict our initial fact.

  4. Negation - Wikipedia

    en.wikipedia.org/wiki/Negation

    As a further example, negation can be defined in terms of NAND and can also be defined in terms of NOR. Algebraically, classical negation corresponds to complementation in a Boolean algebra, and intuitionistic negation to pseudocomplementation in a Heyting algebra. These algebras provide a semantics for classical and intuitionistic logic.

  5. Contraposition - Wikipedia

    en.wikipedia.org/wiki/Contraposition

    " In this case, unlike the last example, the inverse of the statement is true. The converse is "If a polygon has four sides, then it is a quadrilateral." Again, in this case, unlike the last example, the converse of the statement is true. The negation is "There is at least one quadrilateral that does not have four sides.

  6. Literal (mathematical logic) - Wikipedia

    en.wikipedia.org/wiki/Literal_(mathematical_logic)

    A negative literal is the negation of an atom (e.g., ). The polarity of a literal is positive or negative depending on whether it is a positive or negative literal. In logics with double negation elimination (where ¬ ¬ x ≡ x {\displaystyle \lnot \lnot x\equiv x} ) the complementary literal or complement of a literal l {\displaystyle l} can ...

  7. Negation as failure - Wikipedia

    en.wikipedia.org/wiki/Negation_as_failure

    Negation As Failure (NAF, for short) is a non-monotonic inference rule in logic programming, used to derive (i.e. that is assumed not to hold) from failure to derive . Note that n o t p {\displaystyle \mathrm {not} ~p} can be different from the statement ¬ p {\displaystyle \neg p} of the logical negation of p {\displaystyle p} , depending on ...

  8. Prenex normal form - Wikipedia

    en.wikipedia.org/wiki/Prenex_normal_form

    The latter statement says that there exists some natural number n such that if x is less than n, then x is less than zero. Both statements are true. The former statement is true because if x is less than any natural number, it must be less than the smallest natural number (zero). The latter statement is true because n=0 makes the implication a ...

  9. Propositional calculus - Wikipedia

    en.wikipedia.org/wiki/Propositional_calculus

    Propositional logic deals with statements, which are defined as declarative sentences having truth value. [29] [1] Examples of statements might include: Wikipedia is a free online encyclopedia that anyone can edit. London is the capital of England. All Wikipedia editors speak at least three languages.