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Theorem tbw-ax4 1468
Description: The fourth of four axioms in the Tarski-Bernays-Wajsberg system.

This axiom was added to the Tarski-Bernays axiom system ( see tb-ax1 , tb-ax2 , and tb-ax3 in by Wajsberg for completeness. (Contributed by Anthony Hart, 13-Aug-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression

Proof of Theorem tbw-ax4
StepHypRef Expression
1 falim 1328 1
Colors of variables: wff setvar class
Syntax hints:   wi 4   wfal 1317
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 177  df-tru 1319  df-fal 1320
This theorem is referenced by:  tbwlem2  1471  tbwlem4  1473  re1luk3  1477
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