G4 Prover
    
Result of the test for sequent p->q <--> ~q-> ~p 



G4 Prover: a Prolog Prover for Roy Dyckhoff's Sequent Calculus G4
This prover is a fork made by Joseph Vidal-Rosset (joseph.vidal-rosset@gmail.com),
from seqprover.pl, the sequent prover for CL-X, written by Naoyuki Tamura (tamura@kobe-u.ac.jp).
Type "help." if you need some help.
fol(g4i)> fol(g4i).
yes
fol(g4i)> output(pretty).
yes
fol(g4i)> p->q<--> ~q-> ~p.
Trying to prove with threshold = 0
Succeed in proving p->q --> ~q-> ~p (1 msec.)
pretty:1 =
--------------- Ax
bot,q,p --> bot
------------------ L0->1
q,q->bot,p --> bot
--------------------- L0->1
p,q->bot,p->q --> bot
--------------------- R~
 q->bot,p->q --> ~p
 ------------------ L~def
   ~q,p->q --> ~p
   ---------------- R->
   p->q --> ~q-> ~p
Trying to prove with threshold = 0 1 2 3 4 5
Fail to prove ~q-> ~p --> p->q (13 msec.)
yes
fol(g4i)> quit.
yes
Exit from Sequent Calculus Prover...
Total CPU time = 18 msec.
true 


  

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Maintained by  Joseph Vidal-Rosset