Dictionary    Maps    Thesaurus    Translate    Advanced >   


Tip: Click Thesaurus above for synonyms. Also, follow synonym links within the dictionary to find definitions from other sources.

1. The Free On-line Dictionary of Computing (30 December 2018)
first-order logic

    The language describing the truth of
   mathematical formulas.  Formulas describe properties of
   terms and have a truth value.  The following are atomic
   formulas:

    True
    False
    p(t1,..tn)	where t1,..,tn are terms and p is a predicate.

   If F1, F2 and F3 are formulas and v is a variable then the
   following are compound formulas:

    F1 ^ F2	conjunction - true if both F1 and F2 are true,

    F1 V F2	disjunction - true if either or both are true,

    F1 => F2	implication - true if F1 is false or F2 is
   		true, F1 is the antecedent, F2 is the
   		consequent (sometimes written with a thin
   		arrow),

    F1 <= F2	true if F1 is true or F2 is false,

    F1 == F2	true if F1 and F2 are both true or both false
   		(normally written with a three line
   		equivalence symbol)

    ~F1		negation - true if f1 is false (normally
   		written as a dash '-' with a shorter vertical
   		line hanging from its right hand end).

    For all v . F	universal quantification - true if F is true
   		for all values of v (normally written with an
   		inverted A).

    Exists v . F	existential quantification - true if there
   		exists some value of v for which F is true.
   		(Normally written with a reversed E).

   The operators ^ V => <= == ~ are called connectives.  "For
   all" and "Exists" are quantifiers whose scope is F.  A
   term is a mathematical expression involving numbers,
   operators, functions and variables.

   The "order" of a logic specifies what entities "For all" and
   "Exists" may quantify over.  First-order logic can only
   quantify over sets of atomic propositions.  (E.g. For all p
   . p => p).  Second-order logic can quantify over functions on
   propositions, and higher-order logic can quantify over any
   type of entity.  The sets over which quantifiers operate are
   usually implicit but can be deduced from well-formedness
   constraints.

   In first-order logic quantifiers always range over ALL the
   elements of the domain of discourse.  By contrast,
   second-order logic allows one to quantify over subsets.

   ["The Realm of First-Order Logic", Jon Barwise, Handbook of
   Mathematical Logic (Barwise, ed., North Holland, NYC, 1977)].

   (2005-12-27)


Common Misspellings >
Most Popular Searches: Define Misanthrope, Define Pulchritudinous, Define Happy, Define Veracity, Define Cornucopia, Define Almuerzo, Define Atresic, Define URL, Definitions Of Words, Definition Of Get Up, Definition Of Quid Pro Quo, Definition Of Irreconcilable Differences, Definition Of Word, Synonyms of Repetitive, Synonym Dictionary, Synonym Antonyms. See our main index and map index for more details.

©2011-2024 ZebraWords.com - Define Yourself - The Search for Meanings and Meaning Means I Mean. All content subject to terms and conditions as set out here. Contact Us, peruse our Privacy Policy