Tutorial Contents Tutorial Five: Predicate Calculus: Tableaux - The $xj rule - Bad Mistakes and Technical Mistakes - Ticking - Finished Tableaux - Sequents - Soundness and Completeness - Proof of a syntactic sequent: example
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Exercise 5.1

 

1

 Can the "xj rule be applied in the following cases? If it can, what would the result be?
  (i)

Gb

"x[Fx®Rxx
  (ii)

Gb

"x[Fx®Rxa]
  (iii)

$xFx

"x"yRx
  (iv)

["xFxÙ$yRy]

Ga
  (v)

$x"y[Fa®Gxy]
  (vi)

¬¬"y$x[Fa®Gxy]
  (vii)

"y$x[[Fx®Gxy]ÙRay]
  (viii)              
 

 

 

 
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