From ac0146e4142587df45dada4bdf9e0d0faec81a67 Mon Sep 17 00:00:00 2001 From: yoni206 Date: Tue, 15 Jun 2021 09:28:40 -0700 Subject: An example for a quick start guide (#6686) Co-authored-by: Aina Niemetz --- examples/api/cpp/CMakeLists.txt | 1 + examples/api/cpp/quickstart.cpp | 170 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 171 insertions(+) create mode 100644 examples/api/cpp/quickstart.cpp diff --git a/examples/api/cpp/CMakeLists.txt b/examples/api/cpp/CMakeLists.txt index bff7caa4d..6f66fdc5f 100644 --- a/examples/api/cpp/CMakeLists.txt +++ b/examples/api/cpp/CMakeLists.txt @@ -24,6 +24,7 @@ set(CVC5_EXAMPLES_API sets sequences strings + quickstart ) foreach(example ${CVC5_EXAMPLES_API}) diff --git a/examples/api/cpp/quickstart.cpp b/examples/api/cpp/quickstart.cpp new file mode 100644 index 000000000..5d4849bc0 --- /dev/null +++ b/examples/api/cpp/quickstart.cpp @@ -0,0 +1,170 @@ +/****************************************************************************** + * Top contributors (to current version): + * Yoni Zohar + * + * This file is part of the cvc5 project. + * + * Copyright (c) 2009-2021 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. + * **************************************************************************** + * + * A simple demonstration of the api capabilities of cvc5. + * + */ + +#include + +#include + +using namespace std; +using namespace cvc5::api; + +int main() +{ + // Create a solver + Solver solver; + + // We will ask the solver to produce models and unsat cores, + // hence these options should be turned on. + solver.setOption("produce-models", "true"); + solver.setOption("produce-unsat-cores", "true"); + + // The simplest way to set a logic for the solver is to choose "ALL". + // This enables all logics in the solver. + // Alternatively, "QF_ALL" enables all logics without quantifiers. + // To optimize the solver's behavior for a more specific logic, + // use the logic name, e.g. "QF_BV" or "QF_AUFBV". + + // Set the logic + solver.setLogic("ALL"); + + // In this example, we will define constraints over reals and integers. + // Hence, we first obtain the corresponding sorts. + Sort realSort = solver.getRealSort(); + Sort intSort = solver.getIntegerSort(); + + // x and y will be real variables, while a and b will be integer variables. + // Formally, their cpp type is Term, + // and they are called "constants" in SMT jargon: + Term x = solver.mkConst(realSort, "x"); + Term y = solver.mkConst(realSort, "y"); + Term a = solver.mkConst(intSort, "a"); + Term b = solver.mkConst(intSort, "b"); + + // Our constraints regarding x and y will be: + // + // (1) 0 < x + // (2) 0 < y + // (3) x + y < 1 + // (4) x <= y + // + + // Formally, constraints are also terms. Their sort is Boolean. + // We will construct these constraints gradually, + // by defining each of their components. + // We start with the constant numerals 0 and 1: + Term zero = solver.mkReal(0); + Term one = solver.mkReal(1); + + // Next, we construct the term x + y + Term xPlusY = solver.mkTerm(PLUS, x, y); + + // Now we can define the constraints. + // They use the operators +, <=, and <. + // In the API, these are denoted by PLUS, LEQ, and LT. + // A list of available operators is available in: + // src/api/cpp/cvc5_kind.h + Term constraint1 = solver.mkTerm(LT, zero, x); + Term constraint2 = solver.mkTerm(LT, zero, y); + Term constraint3 = solver.mkTerm(LT, xPlusY, one); + Term constraint4 = solver.mkTerm(LEQ, x, y); + + // Now we assert the constraints to the solver. + solver.assertFormula(constraint1); + solver.assertFormula(constraint2); + solver.assertFormula(constraint3); + solver.assertFormula(constraint4); + + // Check if the formula is satisfiable, that is, + // are there real values for x,y,z that satisfy all the constraints? + Result r1 = solver.checkSat(); + + // The result is either SAT, UNSAT, or UNKNOWN. + // In this case, it is SAT. + std::cout << "expected: sat" << std::endl; + std::cout << "result:" << r1 << std::endl; + + // We can get the values for x and y that satisfy the constraints. + Term xVal = solver.getValue(x); + Term yVal = solver.getValue(y); + + // It is also possible to get values for compound terms, + // even if those did not appear in the original formula. + Term xMinusY = solver.mkTerm(MINUS, x, y); + Term xMinusYVal = solver.getValue(xMinusY); + + // We can now obtain thestring representations of the values. + std::string xStr = xVal.getRealValue(); + std::string yStr = yVal.getRealValue(); + std::string xMinusYStr = xMinusYVal.getRealValue(); + + std::cout << "value for x: " << xStr << std::endl; + std::cout << "value for y: " << yStr << std::endl; + std::cout << "value for x - y: " << xMinusYStr << std::endl; + + // Further, we can convert the values to cpp types, + // using standard cpp conversion functions. + double xDouble = std::stod(xStr); + double yDouble = std::stod(yStr); + double xMinusYDouble = std::stod(xMinusYStr); + + // Another way to independently compute the value of x and y would be using + // the ordinary cpp minus operator instead of asking the solver. + // However, for more complex terms, + // it is easier to let the solver do the evaluation. + double xMinusYComputed = xDouble - yDouble; + if (xMinusYComputed == xMinusYDouble) + { + std::cout << "computed correctly" << std::endl; + } + else + { + std::cout << "computed incorrectly" << std::endl; + } + + // Next, we will check satisfiability of the same formula, + // only this time over integer variables a and b. + + // We start by resetting assertions added to the solver. + solver.resetAssertions(); + + // Next, we assert the same assertions above with integers. + // This time, we inline the construction of terms + // to the assertion command. + solver.assertFormula(solver.mkTerm(LT, solver.mkInteger(0), a)); + solver.assertFormula(solver.mkTerm(LT, solver.mkInteger(0), b)); + solver.assertFormula( + solver.mkTerm(LT, solver.mkTerm(PLUS, a, b), solver.mkInteger(1))); + solver.assertFormula(solver.mkTerm(LEQ, a, b)); + + // We check whether the revised assertion is satisfiable. + Result r2 = solver.checkSat(); + + // This time the formula is unsatisfiable + std::cout << "expected: unsat" << std::endl; + std::cout << "result: " << r2 << std::endl; + + // We can query the solver for an unsatisfiable core, i.e., a subset + // of the assertions that is already unsatisfiable. + std::vector unsatCore = solver.getUnsatCore(); + std::cout << "unsat core size: " << unsatCore.size() << std::endl; + std::cout << "unsat core: " << std::endl; + for (const Term& t : unsatCore) + { + std::cout << t << std::endl; + } + + return 0; +} -- cgit v1.2.3