Sindbad~EG File Manager

Length of proof is 5.  Level of proof is 3.
 
---------------- PROOF ----------------
 
15 [] -E(xa,xb,xc,xd)| -E(xc,xd,xe,xf)|E(xa,xb,xe,xf).
22 [] -E(xa,xb,xc,xd)|E(xb,xa,xd,xc).
113 [] s(xa,s(xa,xp))=xp.
118 [] E(xp,xq,s(xa,xp),s(xa,xq)).
178 [] -R(xa,xb,xc)|E(xa,xc,xa,s(xb,xc)).
179 [] R(xa,xb,xc)| -E(xa,xc,xa,s(xb,xc)).
191 [] R(a,b,c).
192 [] -R(c,b,a).
193 [binary,191.1,178.1] E(a,c,a,s(b,c)).
195 [binary,192.1,179.1] -E(c,a,c,s(b,a)).
268 [hyper,15,193,118] E(a,c,s(x,a),s(x,s(b,c))).
299 [binary,195.1,22.2] -E(a,c,s(b,a),c).
17428 [para_into,268.1.4,113.1.1] E(a,c,s(b,a),c).
17429 [binary,17428.1,299.1] $F.