1 | 4. x:Alph*. R(x,x) 5. ( x,y:Alph*. R(x,y)  R(y,x))
& ( x,y,z:Alph*. R(x,y) & R(y,z)  R(x,z))
& ( x,y,z:Alph*. R(x,y)  R((z @ x),z @ y))
& ( w:( n Alph*). l:Alph*. i: n. R(l,w(i))) 6. b: Alph* 7. c: Alph* 8. n@0:  9. l:Alph*. ||l|| < n@0  ( a':Alph*. ||a'|| < n n & R((l @ b),a' @ b) & R((l @ c),a' @ c)) 10. l: Alph* 11. ||l|| = n@0 12. a,b,c:Alph*. ||a|| n n  ( a':Alph*. ||a'|| < ||a|| & R((a @ b),a' @ b) & R((a @ c),a' @ c)) 13. ||l|| < n n R((l @ b),l @ b) & R((l @ c),l @ c) |