Sindbad~EG File Manager

Length of proof is 5.  Level of proof is 3.
 
---------------- PROOF ----------------
 
4 [] T(x,y,ext(x,y,w,v)).
5 [] E(y,ext(x,y,w,v),w,v).
13 [] E(xa,xb,xa,xb).
36 [] alpha!=gamma.
60 [] xa=xb| -T(xa,xb,xc)| -T(xa,xb,xd)|T(xb,xc,xd)|T(xb,xd,xc).
65 [] le(xa,xb,xc,xd)| -T(xa,xb,xe)| -E(xa,xe,xc,xd).
66 [] -le(xa,xb,xc,xd)| -E(xa,xb,xa1,xb1)| -E(xc,xd,xc1,xd1)|le(xa1,xb1,xc1,xd1).
101 [] -le(a,b,c,d).
102 [] -le(c,d,a,b).
110 [ur,66,5,13,101] -le(x,ext(y,x,a,b),c,d).
129 [ur,66,5,13,102] -le(x,ext(y,x,c,d),a,b).
484 [ur,65,110,5] -T(x,ext(y,x,a,b),ext(z,x,c,d)).
793 [ur,65,129,5] -T(x,ext(y,x,c,d),ext(z,x,a,b)).
8995 [ur,60,36,4,4,484] T(gamma,ext(alpha,gamma,c,d),ext(alpha,gamma,a,b)).
8996 [binary,8995.1,793.1] $F.