View source for Existential quantifier

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A logical operation used in forming statements with the expression  "for a certain x"  ( "an x exists for which", "there exists an x such that" ). In formalized languages, existential quantifiers are denoted by $\exists x$, $(\exists x)$, $\cup_x$, $\vee_x$, $\Sigma_x$.

====Comments====
The ''unique existential quantifier'' forms the assertion that "there exists exactly one x such that" and is denoted $\exists!x$.

====References====
<table>
<TR><TD valign="top">[a1]</TD> <TD valign="top">  A. Grzegorczyk,   "An outline of mathematical logic" , Reidel  (1974)</TD></TR>
<TR><TD valign="top">[b1]</TD> <TD valign="top">  S.C. Kleene, "Mathematical Logic" repr. Dover (2013) {{ISBN|0486317072}}</TD></TR>
</table>