Logical Connectives - Common Logical Connectives - History of Notations

History of Notations

  • Negation: the symbol ¬ appeared in Heyting in 1929. (compare to Frege's symbol in his Begriffsschrift); the symbol ~ appeared in Russell in 1908; an alternative notation is to add an horizontal line on top of the formula, as in ; another alternative notation is to use a prime symbol as in P'.
  • Conjunction: the symbol ∧ appeared in Heyting in 1929 (compare to Peano's use of the set-theoretic notation of intersection ∩ ); & appeared at least in Schönfinkel in 1924; . comes from Boole's interpretation of logic as an elementary algebra.
  • Disjunction: the symbol ∨ appeared in Russell in 1908 (compare to Peano's use of the set-theoretic notation of union ∪); the symbol + is also used, in spite of the ambiguity coming from the fact that the + of ordinary elementary algebra is an exclusive or when interpreted logically in a two-element ring; punctually in the history a + together with a dot in the lower right corner has been used by Peirce,
  • Implication: the symbol → can be seen in Hilbert in 1917; ⊃ was used by Russell in 1908 (compare to Peano's inverted C notation); was used in Vax.
  • Biconditional: the symbol ≡ was used at least by Russell in 1908; ↔ was used at least by Tarski in 1940; ⇔ was used in Vax; other symbols appeared punctually in the history such as ⊃⊂ in Gentzen, ~ in Schönfinkel or ⊂⊃ in Chazal.
  • True: the symbol 1 comes from Boole's interpretation of logic as an elementary algebra over the two-element Boolean algebra; other notations include to be found in Peano.
  • False: the symbol 0 comes also from Boole's interpretation of logic as a ring; other notations include to be found in Peano.

Some authors used letters for connectives at some time of the history: u. for conjunction (German's "und" for "and") and o. for disjunction (German's "oder" for "or") in earlier works by Hilbert (1904); Np for negation, Kpq for conjunction, Apq for disjunction, Cpq for implication, Epq for biconditional in Łukasiewicz (1929).

Read more about this topic:  Logical Connectives, Common Logical Connectives

Famous quotes containing the words history of and/or history:

    The history of his present majesty, is a history of unremitting injuries and usurpations ... all of which have in direct object the establishment of an absolute tyranny over these states. To prove this, let facts be submitted to a candid world, for the truth of which we pledge a faith yet unsullied by falsehood.
    Thomas Jefferson (1743–1826)

    There is no history of how bad became better.
    Henry David Thoreau (1817–1862)