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In predicate logic, existential generalization [1] [2] (also known as existential introduction, ∃I) is a valid rule of inference that allows one to move from a specific statement, or one instance, to a quantified generalized statement, or existential proposition.
Each logic operator can be used in an assertion about variables and operations, showing a basic rule of inference. Examples: The column-14 operator (OR), shows Addition rule : when p =T (the hypothesis selects the first two lines of the table), we see (at column-14) that p ∨ q =T.
In predicate logic, an existential quantification is a type of quantifier, a logical constant which is interpreted as "there exists", "there is at least one", or "for some". It is usually denoted by the logical operator symbol ∃, which, when used together with a predicate variable, is called an existential quantifier (" ∃x" or "∃(x)" or ...
The full generalization rule allows for hypotheses to the left of the turnstile, but with restrictions. Assume Γ {\displaystyle \Gamma } is a set of formulas, φ {\displaystyle \varphi } a formula, and Γ ⊢ φ ( y ) {\displaystyle \Gamma \vdash \varphi (y)} has been derived.
existential generalization A rule of inference allowing the conclusion that something exists with a certain property, based on the existence of a particular example. existential import The implication that something exists by the assertion of a particular kind of statement, especially relevant in traditional syllogistic logic. existential ...
Term logic treated All, Some and No in the 4th century BC, in an account also touching on the alethic modalities. In 1827, George Bentham published his Outline of a New System of Logic: With a Critical Examination of Dr. Whately's Elements of Logic, describing the principle of the quantifier, but the book was not widely circulated. [12]
A generalization to infinite domains and infinite signs is easy. A generalization to infinite predicates needs no explanation. A convenient fact is that this logic can also accommodate the domain of the null set, as quantificational claims will not need to assume an element in the domain.
In predicate logic, existential instantiation (also called existential elimination) [1] [2] is a rule of inference which says that, given a formula of the form () (), one may infer () for a new constant symbol c.