Sindbad~EG File Manager

Length of proof is 8.  Level of proof is 4.
 
---------------- PROOF ----------------
 
4 [] T(x,y,ext(x,y,w,v)).
28 [] -T(xa,xb,xc)|T(xc,xb,xa).
284 [] Col(xa,xb,xc)| -T(xa,xb,xc).
324 [] -opposite(xa,xp,xq,xb)| -Col(xp,xq,xb).
325 [] -opposite(xa,xp,xq,xb)|T(xa,il(xa,xb,xp,xq),xb).
326 [] -opposite(xa,xp,xq,xb)|Col(xp,xq,il(xa,xb,xp,xq)).
352 [] c2=ext(p1,p2,p1,a).
353 [] opposite(t,r,cs,c2).
355 [] Col(r,cs,a).
359 [] -T(xc,xb,t)| -Col(p1,p2,xc)| -Col(r,cs,xb)|a=xc.
364 [] il(t,c2,r,cs)=b.
386 [para_from,352.1.2,4.1.3] T(p1,p2,c2).
387 [binary,353.1,326.1,demod,364] Col(r,cs,b).
388 [binary,353.1,325.1,demod,364] T(t,b,c2).
416 [binary,355.1,324.2] -opposite(x,r,cs,a).
540 [binary,386.1,284.2] Col(p1,p2,c2).
635 [binary,388.1,28.1] T(c2,b,t).
690 [binary,635.1,359.1,unit_del,540,387] a=c2.
731 [para_from,690.1.1,416.1.4] -opposite(x,r,cs,c2).
732 [binary,731.1,353.1] $F.