1 | 1. Alph: Type 2. R: Alph* Alph* Prop 3. n:   4. ( x:Alph*. R(x,x))
& ( 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))) 5. a: Alph* 6. b: Alph* 7. c: Alph* a':Alph*. ||a'|| < n n & R((a @ b),a' @ b) & R((a @ c),a' @ c) |