Abstract We prove that the first-order logic of CZF is intuitionistic logic. To do so, we introduce a new model transfinite computation (Set Register Machines) and combine resulting notion realisability with Beth semantics. On way, also show propositional admissible rules are exactly those

for the first time in the history of logic, afzal al-din al-khunaji has found tautologies and contradictories among the verity and actuality propositions. these have been formalized and investigated in first-order logic and it has been shown that their perpetual truth requires the assumption of ‘the presupposed existence of non-existence.’ in this paper, i investigate the tautologies in second-...