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Length of proof is 8.  Level of proof is 4.
 
---------------- PROOF ----------------
 
4 [] T(x,y,ext(x,y,w,v)).
5 [] E(y,ext(x,y,w,v),w,v).
6 [] -E(x,y,x1,y1)| -E(y,z,y1,z1)| -E(x,v,x1,v1)| -E(y,v,y1,v1)| -T(x,y,z)| -T(x1,y1,z1)|x=y|E(z,v,z1,v1).
13 [] E(xa,xb,xa,xb).
21 [] -E(xb,xc,xa,xa)|xb=xc.
25 [] -T(xa,xb,xc)|T(xc,xb,xa).
26 [] T(xa1,xa1,xb1).
28 [] -T(xa,xb,xd)| -T(xb,xc,xd)|T(xa,xb,xc).
29 [] -T(xa,xb,xc)| -T(xa,xc,xd)|T(xb,xc,xd).
30 [] T(a,b,c).
31 [] T(b,c,d).
32 [] b!=c.
33 [] -T(a,c,d).
50 [hyper,29,30,4] T(b,c,ext(a,c,x,y)).
74 [binary,31.1,29.1] -T(b,d,x)|T(c,d,x).
140 [ur,28,4,33] -T(c,d,ext(a,c,x,y)).
692 [hyper,6,13,5,13,13,50,31,unit_del,32] E(ext(a,c,c,d),x,d,x).
733 [binary,74.1,25.2] T(c,d,x)| -T(x,d,b).
4499 [binary,733.1,140.1] -T(ext(a,c,x,y),d,b).
49546 [binary,692.1,21.1] ext(a,c,c,d)=d.
49717 [para_from,49546.1.1,4499.1.1] -T(d,d,b).
49718 [binary,49717.1,26.1] $F.