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
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
#!/usr/bin/env python
#####################
#! \file bitvectors_and_arrays.py
## \verbatim
## Top contributors (to current version):
## Makai Mann
## This file is part of the CVC4 project.
## Copyright (c) 2009-2018 by the authors listed in the file AUTHORS
## in the top-level source directory) and their institutional affiliations.
## All rights reserved. See the file COPYING in the top-level source
## directory for licensing information.\endverbatim
##
## \brief A simple demonstration of the solving capabilities of the CVC4
## bit-vector and array solvers through the Python API. This is a direct
## translation of bitvectors_and_arrays-new.cpp.
import pycvc4
from pycvc4 import kinds
import math
if __name__ == "__main__":
slv = pycvc4.Solver()
slv.setOption("produce-models", "true")
slv.setOption("output-language", "smtlib")
slv.setLogic("QF_AUFBV")
# Consider the following code (where size is some previously defined constant):
#
#
# Assert (current_array[0] > 0);
# for (unsigned i = 1; i < k; ++i) {
# current_array[i] = 2 * current_array[i - 1];
# Assert (current_array[i-1] < current_array[i]);
# }
#
# We want to check whether the assertion in the body of the for loop holds
# throughout the loop.
# Setting up the problem parameters
k = 4
index_size = int(math.ceil(math.log(k, 2)))
# Sorts
elementSort = slv.mkBitVectorSort(32)
indexSort = slv.mkBitVectorSort(index_size)
arraySort = slv.mkArraySort(indexSort, elementSort)
# Variables
current_array = slv.mkConst(arraySort, "current_array")
# Making a bit-vector constant
zero = slv.mkBitVector(index_size, 0)
# Test making a constant array
constarr0 = slv.mkConstArray(arraySort, slv.mkBitVector(32, 0))
# Asserting that current_array[0] > 0
current_array0 = slv.mkTerm(kinds.Select, current_array, zero)
current_array0_gt_0 = slv.mkTerm(kinds.BVSgt,
current_array0,
slv.mkBitVector(32, 0))
slv.assertFormula(current_array0_gt_0)
# Building the assertions in the loop unrolling
index = slv.mkBitVector(index_size, 0)
old_current = slv.mkTerm(kinds.Select, current_array, index)
two = slv.mkBitVector(32, 2)
assertions = []
for i in range(1, k):
index = slv.mkBitVector(index_size, i)
new_current = slv.mkTerm(kinds.BVMult, two, old_current)
# current[i] = 2*current[i-1]
current_array = slv.mkTerm(kinds.Store, current_array, index, new_current)
# current[i-1] < current[i]
current_slt_new_current = slv.mkTerm(kinds.BVSlt, old_current, new_current)
assertions.append(current_slt_new_current)
old_current = slv.mkTerm(kinds.Select, current_array, index)
query = slv.mkTerm(kinds.Not, slv.mkTerm(kinds.And, assertions))
print("Asserting {} to CVC4".format(query))
slv.assertFormula(query)
print("Expect sat.")
print("CVC4:", slv.checkSatAssuming(slv.mkTrue()))
# Getting the model
print("The satisfying model is: ")
print(" current_array =", slv.getValue(current_array))
print(" current_array[0]", slv.getValue(current_array0))
|
