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(in-package "PROOF-CHECKER-ITP13")
;; ===================================================================
;; ============================ VARIABLES ============================
; Consider posp
(defun variablep (x)
(declare (xargs :guard t))
(and (integerp x)
(< 0 x)))
;; ===================================================================
;; ============================ LITERALS =============================
(defun literalp (x)
(declare (xargs :guard t))
(and (integerp x)
(not (equal x 0))))
(defthm literalp-implies-eqlablep
(implies (literalp x)
(eqlablep x)))
;; ===================================================================
;; ========================== LITERAL-LIST ===========================
(defun literal-listp (x)
(declare (xargs :guard t))
(if (atom x)
(null x)
(and (literalp (car x))
(literal-listp (cdr x)))))
(defthm literal-listp-implies-eqlable-listp
(implies (literal-listp x)
(eqlable-listp x)))
(defthm literal-listp-implies-literalp-member
(implies (and (literal-listp x)
(member e x))
(literalp e)))
(defthm literal-listp-append
(implies (and (literal-listp x)
(literal-listp y))
(literal-listp (append x y))))
;; ===================================================================
;; ============================ NEGATION =============================
(defun negatedp (x)
(declare (xargs :guard (literalp x)))
(< x 0))
(defun negate (x)
(declare (xargs :guard (literalp x)))
(- x))
(defthm literalp-negate
(equal (literalp (negate x))
(literalp x)))
(defthm literalp-implies-not-equal-negate
(implies (literalp x)
(not (equal (negate x) x))))
(defthm negate-negate
(implies (literalp x)
(equal (negate (negate x))
x)))
;; ===================================================================
;; ============================ DISABLES =============================
(in-theory (disable variablep
literalp
;literal-listp
negatedp
negate
;literal-to-variable
;variable-to-natural
;natp ; needed to prevent acl2 from going crazy
))
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