View source for Refutable formula

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''formally refutable formula, in a given system of formulas''

A closed formula of the given system whose negation can be deduced in this system.



====Comments====
A closed formula $A$ in a given logical system is formally decidable (cf. [[Decidable formula|Decidable formula]]) if $A$ is either provable or refutable.

====References====
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  S.C. Kleene,   "Introduction to metamathematics" , North-Holland  (1959)  pp. 194ff</TD></TR></table>