1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
|
#! /usr/bin/python
##! \file SimpleVC.py
### \verbatim
### Original author: mdeters
### Major contributors: none
### Minor contributors (to current version): none
### This file is part of the CVC4 prototype.
### Copyright (c) 2009, 2010, 2011 The Analysis of Computer Systems Group (ACSys)
### Courant Institute of Mathematical Sciences
### New York University
### See the file COPYING in the top-level source directory for licensing
### information.\endverbatim
###
### \brief A simple demonstration of the Python interface
###
### A simple demonstration of the Python interface. Compare to the
### C++ interface in simple_vc_cxx.cpp; they are quite similar.
###
### To run, use something like:
###
### ln -s ../builds/src/bindings/python/CVC4.py CVC4.py
### ln -s ../builds/src/bindings/python/.libs/CVC4.so _CVC4.so
### ./SimpleVC.py
####
import CVC4
from CVC4 import ExprManager, SmtEngine, Rational, Expr
import sys
def main():
em = ExprManager()
smt = SmtEngine(em)
# Prove that for integers x and y:
# x > 0 AND y > 0 => 2x + y >= 3
integer = em.integerType()
x = em.mkVar("x", integer)
y = em.mkVar("y", integer)
zero = em.mkConst(Rational(0))
x_positive = em.mkExpr(CVC4.GT, x, zero)
y_positive = em.mkExpr(CVC4.GT, y, zero)
two = em.mkConst(Rational(2))
twox = em.mkExpr(CVC4.MULT, two, x)
twox_plus_y = em.mkExpr(CVC4.PLUS, twox, y)
three = em.mkConst(Rational(3))
twox_plus_y_geq_3 = em.mkExpr(CVC4.GEQ, twox_plus_y, three)
formula = Expr(em.mkExpr(CVC4.AND, x_positive, y_positive)).impExpr(Expr(twox_plus_y_geq_3))
print "Checking validity of formula " + formula.toString() + " with CVC4."
print "CVC4 should report VALID."
print "Result from CVC4 is: " + smt.query(formula).toString()
return 0
if __name__ == '__main__':
sys.exit(main())
|