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#!/usr/bin/env python
#####################
#! \file sygus-fun.py
## \verbatim
## Top contributors (to current version):
## Yoni Zohar
## This file is part of the CVC4 project.
## Copyright (c) 2009-2018 by the authors listed in the file AUTHkinds.OrS
## 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
## sygus solver through the Python API. This is a direct
## translation of sygus-fun.cpp.
#####################
import copy
import pycvc4
from pycvc4 import kinds
if __name__ == "__main__":
slv = pycvc4.Solver()
# required options
slv.setOption("lang", "sygus2")
slv.setOption("incremental", "false")
# set the logic
slv.setLogic("LIA")
integer = slv.getIntegerSort()
boolean = slv.getBooleanSort()
# declare input variables for the functions-to-synthesize
x = slv.mkVar(integer, "x")
y = slv.mkVar(integer, "y")
# declare the grammar non-terminals
start = slv.mkVar(integer, "Start")
start_bool = slv.mkVar(boolean, "StartBool")
# define the rules
zero = slv.mkReal(0)
one = slv.mkReal(1)
plus = slv.mkTerm(kinds.Plus, start, start)
minus = slv.mkTerm(kinds.Minus, start, start)
ite = slv.mkTerm(kinds.Ite, start_bool, start, start)
And = slv.mkTerm(kinds.And, start_bool, start_bool)
Not = slv.mkTerm(kinds.Not, start_bool)
leq = slv.mkTerm(kinds.Leq, start, start)
# create the grammar object
g = slv.mkSygusGrammar({x, y}, {start, start_bool})
# bind each non-terminal to its rules
g.addRules(start, {zero, one, x, y, plus, minus, ite})
g.addRules(start_bool, {And, Not, leq})
# declare the functions-to-synthesize. Optionally, provide the grammar
# constraints
max = slv.synthFun("max", {x, y}, integer, g)
min = slv.synthFun("min", {x, y}, integer)
# declare universal variables.
varX = slv.mkSygusVar(integer, "x")
varY = slv.mkSygusVar(integer, "y")
max_x_y = slv.mkTerm(kinds.ApplyUf, max, varX, varY)
min_x_y = slv.mkTerm(kinds.ApplyUf, min, varX, varY)
# add semantic constraints
# (constraint (>= (max x y) x))
slv.addSygusConstraint(slv.mkTerm(kinds.Geq, max_x_y, varX))
# (constraint (>= (max x y) y))
slv.addSygusConstraint(slv.mkTerm(kinds.Geq, max_x_y, varY))
# (constraint (or (= x (max x y))
# (= y (max x y))))
slv.addSygusConstraint(slv.mkTerm(
kinds.Or, slv.mkTerm(kinds.Equal, max_x_y, varX), slv.mkTerm(kinds.Equal, max_x_y, varY)))
# (constraint (= (+ (max x y) (min x y))
# (+ x y)))
slv.addSygusConstraint(slv.mkTerm(
kinds.Equal, slv.mkTerm(kinds.Plus, max_x_y, min_x_y), slv.mkTerm(kinds.Plus, varX, varY)))
# print solutions if available
if (slv.checkSynth().isUnsat()):
# Output should be equivalent to:
# (define-fun max ((x Int) (y Int)) Int (ite (<= x y) y x))
# (define-fun min ((x Int) (y Int)) Int (ite (<= x y) x y))
slv.printSynthSolution()
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