Examples for using sygus python api (#4822)

This PR adds examples for using the sygus python api.
The examples are obtained from the examples of the cpp sygus api.

3 files changed, 250 insertions, 0 deletions

diff --git a/examples/api/python/sygus-fun.py b/examples/api/python/sygus-fun.py
new file mode 100644
index 000000000..0f53bd343
--- /dev/null
+++ b/examples/api/python/sygus-fun.py
@@ -0,0 +1,97 @@
+#!/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()
+
diff --git a/examples/api/python/sygus-grammar.py b/examples/api/python/sygus-grammar.py
new file mode 100644
index 000000000..efba88286
--- /dev/null
+++ b/examples/api/python/sygus-grammar.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python
+#####################
+#! \file sygus-grammar.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 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
+## sygus solver through the Python API. This is a direct
+## translation of sygus-grammar.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 variable for the function-to-synthesize
+  x = slv.mkVar(integer, "x")
+
+  # declare the grammar non-terminal
+  start = slv.mkVar(integer, "Start")
+
+  # define the rules
+  zero = slv.mkReal(0)
+  neg_x = slv.mkTerm(kinds.Uminus, x)
+  plus = slv.mkTerm(kinds.Plus, x, start)
+
+  # create the grammar object
+  g1 = slv.mkSygusGrammar({x}, {start})
+  g2 = slv.mkSygusGrammar({x}, {start})
+  g3 = slv.mkSygusGrammar({x}, {start})
+
+  # bind each non-terminal to its rules
+  g1.addRules(start, {neg_x, plus})
+  g2.addRules(start, {neg_x, plus})
+  g3.addRules(start, {neg_x, plus})
+
+  # add parameters as rules for the start symbol. Similar to "(Variable Int)"
+  g2.addAnyVariable(start)
+
+  # declare the functions-to-synthesize
+  id1 = slv.synthFun("id1", {x}, integer, g1)
+  id2 = slv.synthFun("id2", {x}, integer, g2)
+
+  g3.addRule(start, zero)
+
+  id3 = slv.synthFun("id3", {x}, integer, g3)
+
+  # g1 is reusable as long as it remains unmodified after first use
+  id4 = slv.synthFun("id4", {x}, integer, g1)
+
+  # declare universal variables.
+  varX = slv.mkSygusVar(integer, "x")
+
+  id1_x = slv.mkTerm(kinds.ApplyUf, id1, varX)
+  id2_x = slv.mkTerm(kinds.ApplyUf, id2, varX)
+  id3_x = slv.mkTerm(kinds.ApplyUf, id3, varX)
+  id4_x = slv.mkTerm(kinds.ApplyUf, id4, varX)
+
+  # add semantic constraints
+  # (constraint (= (id1 x) (id2 x) (id3 x) (id4 x) x))
+  slv.addSygusConstraint(slv.mkTerm(kinds.And, [slv.mkTerm(kinds.Equal, id1_x, id2_x), slv.mkTerm(kinds.Equal, id1_x, id3_x), slv.mkTerm(kinds.Equal, id1_x, id4_x), slv.mkTerm(kinds.Equal, id1_x, varX)]))
+
+  # print solutions if available
+  if (slv.checkSynth().isUnsat()):
+    # Output should be equivalent to:
+    # (define-fun id1 ((x Int)) Int (+ x (+ x (- x))))
+    # (define-fun id2 ((x Int)) Int x)
+    # (define-fun id3 ((x Int)) Int (+ x 0))
+    # (define-fun id4 ((x Int)) Int (+ x (+ x (- x))))
+    slv.printSynthSolution()
diff --git a/examples/api/python/sygus-inv.py b/examples/api/python/sygus-inv.py
new file mode 100644
index 000000000..cb21e1849
--- /dev/null
+++ b/examples/api/python/sygus-inv.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+
+#####################
+#! \file sygus-inv.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 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
+## sygus solver through the Python API. This is a direct
+## translation of sygus-inv.cpp .
+#####################
+
+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()
+
+  zero = slv.mkReal(0)
+  one = slv.mkReal(1)
+  ten = slv.mkReal(10)
+
+  # declare input variables for functions
+  x = slv.mkVar(integer, "x")
+  xp = slv.mkVar(integer, "xp")
+
+  # (ite (< x 10) (= xp (+ x 1)) (= xp x))
+  ite = slv.mkTerm(kinds.Ite,
+                        slv.mkTerm(kinds.Lt, x, ten),
+                        slv.mkTerm(kinds.Equal, xp, slv.mkTerm(kinds.Plus, x, one)),
+                        slv.mkTerm(kinds.Equal, xp, x))
+
+  # define the pre-conditions, transition relations, and post-conditions
+  pre_f = slv.defineFun("pre-f", {x}, boolean, slv.mkTerm(kinds.Equal, x, zero))
+  trans_f = slv.defineFun("trans-f", {x, xp}, boolean, ite)
+  post_f = slv.defineFun("post-f", {x}, boolean, slv.mkTerm(kinds.Leq, x, ten))
+
+  # declare the invariant-to-synthesize
+  inv_f = slv.synthInv("inv-f", {x})
+
+  slv.addSygusInvConstraint(inv_f, pre_f, trans_f, post_f)
+
+  # print solutions if available
+  if slv.checkSynth().isUnsat():
+    # Output should be equivalent to:
+    # (define-fun inv-f ((x Int)) Bool (not (>= x 11)))
+    slv.printSynthSolution()
+
+
+