Def onto('a;'b;f) == y:'b. x:'a. y = f(x)

is mentioned by

Def suc_rep == x:. (@f:. (one_one(;;f) & onto(;;f)))(x)

[hsuc_rep]

In prior sections: hol bool

Try larger context: HOLlib IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html