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Revisiting the Admission of App

Revisiting the Admission of App

Here is the definition of app again with certain parts highlighted. If you are taking the Walking Tour, please read the text carefully and click on each of the links below, except those marked . Then come back here.

ACL2 !>(defun app (x y) 
  (cond ((endp x) y) 
        (t (cons (car x)  
                 (app (cdr x) y))))) 
 
The admission of APP is trivial, using the 
relation o<  (which is known to be well-founded on 
the domain recognized by o-p ) and the measure 
(ACL2-count  X).  We observe that the 
type of APP is described by the theorem (OR 
(CONSP (APP X Y)) (EQUAL (APP X Y) Y)).  We used primitive type 
reasoning. 
 
Summary 
Form:  ( DEFUN APP ...) 
Rules: ((:FAKE-RUNE-FOR-TYPE-SET NIL)) 
Warnings:  None 
Time:  0.03 seconds (prove: 0.00, print: 0.00, other: 0.03) 
 APP