12 files changed, 517 insertions, 2 deletions

diff --git a/cmake/FindCxxTest.cmake b/cmake/FindCxxTest.cmake
index cd7aed70d..19fd7f881 100644
--- a/cmake/FindCxxTest.cmake
+++ b/cmake/FindCxxTest.cmake
@@ -26,7 +26,7 @@ endif()
 
 if(PYTHONINTERP_FOUND AND CxxTest_PYTHON_TESTGEN_EXECUTABLE)
   set(CxxTest_TESTGEN_EXECUTABLE ${CxxTest_PYTHON_TESTGEN_EXECUTABLE})
-  set(CxxTest_TESTGEN_INTERPRETER ${PYTHON_EXECUTABLE})
+  # set(CxxTest_TESTGEN_INTERPRETER ${PYTHON_EXECUTABLE})
 elseif(PERL_FOUND AND CxxTest_PERL_TESTGEN_EXECUTABLE)
   set(CxxTest_TESTGEN_EXECUTABLE ${CxxTest_PERL_TESTGEN_EXECUTABLE})
   set(CxxTest_TESTGEN_INTERPRETER ${PERL_EXECUTABLE})
diff --git a/src/theory/strings/regexp_operation.cpp b/src/theory/strings/regexp_operation.cpp
index 7286e2fb4..b410670e5 100644
--- a/src/theory/strings/regexp_operation.cpp
+++ b/src/theory/strings/regexp_operation.cpp
@@ -19,6 +19,7 @@
 #include "expr/kind.h"
 #include "options/strings_options.h"
 #include "theory/strings/theory_strings_rewriter.h"
+#include "theory/strings/theory_strings_utils.h"
 
 using namespace CVC4;
 using namespace CVC4::kind;
@@ -1652,6 +1653,115 @@ std::string RegExpOpr::mkString( Node r ) {
   return retStr;
 }
 
+bool RegExpOpr::regExpIncludes(Node r1, Node r2)
+{
+  Assert(Rewriter::rewrite(r1) == r1);
+  Assert(Rewriter::rewrite(r2) == r2);
+
+  if (r1 == r2)
+  {
+    return true;
+  }
+
+  // This method only works on a fragment of regular expressions
+  if (!utils::isSimpleRegExp(r1) || !utils::isSimpleRegExp(r2))
+  {
+    return false;
+  }
+
+  const auto& it = d_inclusionCache.find(std::make_pair(r1, r2));
+  if (it != d_inclusionCache.end())
+  {
+    return (*it).second;
+  }
+
+  std::vector<Node> v1, v2;
+  utils::getRegexpComponents(r1, v1);
+  utils::getRegexpComponents(r2, v2);
+
+  // In the following, we iterate over `r2` (the "includee") and try to
+  // match it with `r1`. `idxs`/`newIdxs` keep track of all the possible
+  // positions in `r1` that we could currently be at.
+  std::unordered_set<size_t> newIdxs = {0};
+  std::unordered_set<size_t> idxs;
+  for (const Node& n2 : v2)
+  {
+    // Transfer elements from `newIdxs` to `idxs`. Out-of-bound indices are
+    // removed and for (re.* re.allchar), we additionally include the
+    // option of skipping it.
+    idxs.clear();
+    for (size_t idx : newIdxs)
+    {
+      if (idx < v1.size())
+      {
+        idxs.insert(idx);
+        if (v1[idx] == d_sigma_star)
+        {
+          Assert(idx + 1 == v1.size() || v1[idx + 1] != d_sigma_star);
+          idxs.insert(idx + 1);
+        }
+      }
+    }
+    newIdxs.clear();
+
+    if (n2.getKind() == STRING_TO_REGEXP || n2 == d_sigma)
+    {
+      Assert(n2 == d_sigma
+             || (n2[0].isConst() && n2[0].getConst<String>().size() == 1));
+      for (size_t idx : idxs)
+      {
+        if (v1[idx] == d_sigma || v1[idx] == n2)
+        {
+          // Given a character or an re.allchar in `r2`, we can either
+          // match it with a corresponding character in `r1` or an
+          // re.allchar
+          newIdxs.insert(idx + 1);
+        }
+      }
+    }
+
+    for (size_t idx : idxs)
+    {
+      if (v1[idx] == d_sigma_star)
+      {
+        // (re.* re.allchar) can match an arbitrary amount of `r2`
+        newIdxs.insert(idx);
+      }
+      else if (utils::isUnboundedWildcard(v1, idx))
+      {
+        // If a series of re.allchar is followed by (re.* re.allchar), we
+        // can decide not to "waste" the re.allchar because the order of
+        // the two wildcards is not observable (i.e. it does not change
+        // the sequences matched by the regular expression)
+        newIdxs.insert(idx);
+      }
+    }
+
+    if (newIdxs.empty())
+    {
+      // If there are no candidates, we can't match the remainder of r2
+      d_inclusionCache[std::make_pair(r1, r2)] = false;
+      return false;
+    }
+  }
+
+  // We have processed all of `r2`. We are now looking if there was also a
+  // path to the end in `r1`. This makes sure that we don't have leftover
+  // bits in `r1` that don't match anything in `r2`.
+  bool result = false;
+  for (size_t idx : newIdxs)
+  {
+    if (idx == v1.size() || (idx == v1.size() - 1 && v1[idx] == d_sigma_star))
+    {
+      result = true;
+      break;
+    }
+  }
+
+  d_inclusionCache[std::make_pair(r1, r2)] = result;
+  return result;
+}
+
 }/* CVC4::theory::strings namespace */
 }/* CVC4::theory namespace */
 }/* CVC4 namespace */
diff --git a/src/theory/strings/regexp_operation.h b/src/theory/strings/regexp_operation.h
index cb35b37c6..117449d35 100644
--- a/src/theory/strings/regexp_operation.h
+++ b/src/theory/strings/regexp_operation.h
@@ -85,6 +85,7 @@ class RegExpOpr {
   std::map<Node, Node> d_rm_inter_cache;
   std::map<Node, bool> d_norv_cache;
   std::map<Node, std::vector<PairNodes> > d_split_cache;
+  std::map<PairNodes, bool> d_inclusionCache;
   void simplifyPRegExp(Node s, Node r, std::vector<Node> &new_nodes);
   void simplifyNRegExp(Node s, Node r, std::vector<Node> &new_nodes);
   /**
@@ -129,6 +130,21 @@ class RegExpOpr {
   Node intersect(Node r1, Node r2, bool &spflag);
   /** Get the pretty printed version of the regular expression r */
   static std::string mkString(Node r);
+
+  /**
+   * Returns true if we can show that the regular expression `r1` includes
+   * the regular expression `r2` (i.e. `r1` matches a superset of sequences
+   * that `r2` matches). This method only works on a fragment of regular
+   * expressions, specifically regular expressions that pass the
+   * `isSimpleRegExp` check.
+   *
+   * @param r1 The regular expression that may include `r2` (must be in
+   *           rewritten form)
+   * @param r2 The regular expression that may be included by `r1` (must be
+   *           in rewritten form)
+   * @return True if the inclusion can be shown, false otherwise
+   */
+  bool regExpIncludes(Node r1, Node r2);
 };
 
 }/* CVC4::theory::strings namespace */
diff --git a/src/theory/strings/regexp_solver.cpp b/src/theory/strings/regexp_solver.cpp
index ea38c4dd9..db4c9012c 100644
--- a/src/theory/strings/regexp_solver.cpp
+++ b/src/theory/strings/regexp_solver.cpp
@@ -65,9 +65,15 @@ void RegExpSolver::check(const std::map<Node, std::vector<Node> >& mems)
   Trace("regexp-process") << "Checking Memberships ... " << std::endl;
   for (const std::pair<const Node, std::vector<Node> >& mr : mems)
   {
+    std::vector<Node> mems = mr.second;
     Trace("regexp-process")
         << "Memberships(" << mr.first << ") = " << mr.second << std::endl;
-    if (!checkEqcIntersect(mr.second))
+    if (!checkEqcInclusion(mems))
+    {
+      // conflict discovered, return
+      return;
+    }
+    if (!checkEqcIntersect(mems))
     {
       // conflict discovered, return
       return;
@@ -271,6 +277,90 @@ void RegExpSolver::check(const std::map<Node, std::vector<Node> >& mems)
   }
 }
 
+bool RegExpSolver::checkEqcInclusion(std::vector<Node>& mems)
+{
+  std::unordered_set<Node, NodeHashFunction> remove;
+
+  for (const Node& m1 : mems)
+  {
+    bool m1Neg = m1.getKind() == NOT;
+    Node m1Lit = m1Neg ? m1[0] : m1;
+
+    if (remove.find(m1) != remove.end())
+    {
+      // Skip memberships marked for removal
+      continue;
+    }
+
+    for (const Node& m2 : mems)
+    {
+      if (m1 == m2)
+      {
+        continue;
+      }
+
+      bool m2Neg = m2.getKind() == NOT;
+      Node m2Lit = m2Neg ? m2[0] : m2;
+
+      // Both regular expression memberships have the same polarity
+      if (m1Neg == m2Neg)
+      {
+        if (d_regexp_opr.regExpIncludes(m1Lit[1], m2Lit[1]))
+        {
+          if (m1Neg)
+          {
+            // ~str.in.re(x, R1) includes ~str.in.re(x, R2) --->
+            //   mark ~str.in.re(x, R2) as reduced
+            d_parent.getExtTheory()->markReduced(m2Lit);
+            remove.insert(m2);
+          }
+          else
+          {
+            // str.in.re(x, R1) includes str.in.re(x, R2) --->
+            //   mark str.in.re(x, R1) as reduced
+            d_parent.getExtTheory()->markReduced(m1Lit);
+            remove.insert(m1);
+
+            // We don't need to process m1 anymore
+            break;
+          }
+        }
+      }
+      else
+      {
+        Node pos = m1Neg ? m2Lit : m1Lit;
+        Node neg = m1Neg ? m1Lit : m2Lit;
+        if (d_regexp_opr.regExpIncludes(neg[1], pos[1]))
+        {
+          // We have a conflict because we have a case where str.in.re(x, R1)
+          // and ~str.in.re(x, R2) but R2 includes R1, so there is no
+          // possible value for x that satisfies both memberships.
+          std::vector<Node> vec_nodes;
+          vec_nodes.push_back(pos);
+          vec_nodes.push_back(neg.negate());
+
+          if (pos[0] != neg[0])
+          {
+            vec_nodes.push_back(pos[0].eqNode(neg[0]));
+          }
+
+          Node conc;
+          d_im.sendInference(vec_nodes, conc, "Intersect inclusion", true);
+          return false;
+        }
+      }
+    }
+  }
+
+  mems.erase(std::remove_if(
+                 mems.begin(),
+                 mems.end(),
+                 [&remove](Node& n) { return remove.find(n) != remove.end(); }),
+             mems.end());
+
+  return true;
+}
+
 bool RegExpSolver::checkEqcIntersect(const std::vector<Node>& mems)
 {
   // do not compute intersections if the re intersection mode is none
diff --git a/src/theory/strings/regexp_solver.h b/src/theory/strings/regexp_solver.h
index f3abb2a1d..c4d6afda0 100644
--- a/src/theory/strings/regexp_solver.h
+++ b/src/theory/strings/regexp_solver.h
@@ -64,6 +64,23 @@ class RegExpSolver
 
  private:
   /**
+   * Check memberships in equivalence class for regular expression
+   * inclusion.
+   *
+   * This method returns false if it discovered a conflict for this set of
+   * assertions, and true otherwise. It discovers a conflict e.g. if mems
+   * contains str.in.re(xi, Ri) and ~str.in.re(xj, Rj) and Rj includes Ri.
+   *
+   * @param mems Vector of memberships of the form: (~)str.in.re(x1, R1)
+   *             ... (~)str.in.re(xn, Rn) where x1 = ... = xn in the
+   *             current context. The function removes elements from this
+   *             vector that were marked as reduced.
+   * @param expForRe Additional explanations for regular expressions.
+   * @return False if a conflict was detected, true otherwise
+   */
+  bool checkEqcInclusion(std::vector<Node>& mems);
+
+  /**
    * Check memberships for equivalence class.
    * The vector mems is a vector of memberships of the form:
    *   (~) (x1 in R1 ) ... (~) (xn in Rn)
diff --git a/src/theory/strings/theory_strings_utils.cpp b/src/theory/strings/theory_strings_utils.cpp
index d3ae5384e..d764b87c1 100644
--- a/src/theory/strings/theory_strings_utils.cpp
+++ b/src/theory/strings/theory_strings_utils.cpp
@@ -134,6 +134,73 @@ Node getConstantEndpoint(Node e, bool isSuf)
   return getConstantComponent(e);
 }
 
+bool isUnboundedWildcard(const std::vector<Node>& rs, size_t start)
+{
+  size_t i = start;
+  while (i < rs.size() && rs[i].getKind() == REGEXP_SIGMA)
+  {
+    i++;
+  }
+
+  if (i >= rs.size())
+  {
+    return false;
+  }
+
+  return rs[i].getKind() == REGEXP_STAR && rs[i][0].getKind() == REGEXP_SIGMA;
+}
+
+bool isSimpleRegExp(Node r)
+{
+  Assert(r.getType().isRegExp());
+
+  std::vector<Node> v;
+  utils::getConcat(r, v);
+  for (const Node& n : v)
+  {
+    if (n.getKind() == STRING_TO_REGEXP)
+    {
+      if (!n[0].isConst())
+      {
+        return false;
+      }
+    }
+    else if (n.getKind() != REGEXP_SIGMA
+             && (n.getKind() != REGEXP_STAR || n[0].getKind() != REGEXP_SIGMA))
+    {
+      return false;
+    }
+  }
+  return true;
+}
+
+void getRegexpComponents(Node r, std::vector<Node>& result)
+{
+  Assert(r.getType().isRegExp());
+
+  NodeManager* nm = NodeManager::currentNM();
+  if (r.getKind() == REGEXP_CONCAT)
+  {
+    for (const Node& n : r)
+    {
+      getRegexpComponents(n, result);
+    }
+  }
+  else if (r.getKind() == STRING_TO_REGEXP && r[0].isConst())
+  {
+    String s = r[0].getConst<String>();
+    for (size_t i = 0, size = s.size(); i < size; i++)
+    {
+      result.push_back(
+          nm->mkNode(STRING_TO_REGEXP, nm->mkConst(s.substr(i, 1))));
+    }
+  }
+  else
+  {
+    result.push_back(r);
+  }
+}
+
 }  // namespace utils
 }  // namespace strings
 }  // namespace theory
diff --git a/src/theory/strings/theory_strings_utils.h b/src/theory/strings/theory_strings_utils.h
index 57d882625..cadc98df3 100644
--- a/src/theory/strings/theory_strings_utils.h
+++ b/src/theory/strings/theory_strings_utils.h
@@ -78,6 +78,39 @@ Node getConstantComponent(Node t);
  */
 Node getConstantEndpoint(Node e, bool isSuf);
 
+/**
+ * Given a vector of regular expression nodes and a start index that points to
+ * a wildcard, returns true if the wildcard is unbounded (i.e. it is followed
+ * by an arbitrary number of `re.allchar`s and then an `re.*(re.allchar)`. If
+ * the start index is not a wilcard or the wildcards are not followed by
+ * `re.*(re.allchar)`, the function returns false.
+ *
+ * @param rs The vector of regular expression nodes
+ * @param start The start index to consider
+ * @return True if the wilcard pointed to by `start` is unbounded, false
+ *         otherwise
+ */
+bool isUnboundedWildcard(const std::vector<Node>& rs, size_t start);
+
+/**
+ * Returns true iff the given regular expression only consists of re.++,
+ * re.allchar, (re.* re.allchar), and str.to.re of string literals.
+ *
+ * @param r The regular expression to check
+ * @return True if the regular expression is simple
+ */
+bool isSimpleRegExp(Node r);
+
+/**
+ * Helper function that takes a regular expression concatenation and
+ * returns the components of the concatenation. Letters of string literals
+ * are treated as individual components.
+ *
+ * @param r The regular expression
+ * @param result The resulting components
+ */
+void getRegexpComponents(Node r, std::vector<Node>& result);
+
 }  // namespace utils
 }  // namespace strings
 }  // namespace theory
diff --git a/test/regress/CMakeLists.txt b/test/regress/CMakeLists.txt
index 80b7c33bf..444a740ea 100644
--- a/test/regress/CMakeLists.txt
+++ b/test/regress/CMakeLists.txt
@@ -862,6 +862,8 @@ set(regress_0_tests
   regress0/strings/norn-31.smt2
   regress0/strings/norn-simp-rew.smt2
   regress0/strings/re.all.smt2
+  regress0/strings/regexp_inclusion.smt2
+  regress0/strings/regexp_inclusion_reduction.smt2
   regress0/strings/repl-rewrites2.smt2
   regress0/strings/replace-const.smt2
   regress0/strings/replaceall-eval.smt2
diff --git a/test/regress/regress0/strings/regexp_inclusion.smt2 b/test/regress/regress0/strings/regexp_inclusion.smt2
new file mode 100644
index 000000000..c5c68a408
--- /dev/null
+++ b/test/regress/regress0/strings/regexp_inclusion.smt2
@@ -0,0 +1,13 @@
+; COMMAND-LINE: --strings-exp --no-re-elim
+(set-info :status unsat)
+(set-logic ALL)
+(declare-const actionName String)
+
+(assert
+(str.in.re actionName (re.++ (str.to.re "wiz") (re.* re.allchar) (str.to.re "foobar") (re.* re.allchar) (str.to.re "baz/") (re.* re.allchar))))
+
+(assert (not
+(str.in.re actionName (re.++ (str.to.re "wiz") (re.* re.allchar) (re.++ (str.to.re "foo") re.allchar (str.to.re "ar")) (re.* re.allchar) (str.to.re "baz/") (re.* re.allchar)))
+))
+
+(check-sat)
diff --git a/test/regress/regress0/strings/regexp_inclusion_reduction.smt2 b/test/regress/regress0/strings/regexp_inclusion_reduction.smt2
new file mode 100644
index 000000000..c10c287bb
--- /dev/null
+++ b/test/regress/regress0/strings/regexp_inclusion_reduction.smt2
@@ -0,0 +1,14 @@
+; COMMAND-LINE: --strings-exp --no-re-elim
+(set-info :status sat)
+(set-logic QF_SLIA)
+(declare-const x String)
+(declare-const y String)
+
+(assert (str.in.re x (re.++ (str.to.re "bar") (re.* re.allchar) (str.to.re "bar"))))
+(assert (str.in.re x (re.++ (str.to.re "ba") re.allchar (re.* re.allchar) (str.to.re "bar"))))
+
+(assert (not (str.in.re y (re.++ (str.to.re "bar") (re.* re.allchar) (str.to.re "bar")))))
+(assert (not (str.in.re y (re.++ (str.to.re "ba") re.allchar (re.* re.allchar) (str.to.re "bar")))))
+(assert (not (= y "")))
+
+(check-sat)
diff --git a/test/unit/theory/CMakeLists.txt b/test/unit/theory/CMakeLists.txt
index 963466b09..02ca5d8b5 100644
--- a/test/unit/theory/CMakeLists.txt
+++ b/test/unit/theory/CMakeLists.txt
@@ -1,3 +1,4 @@
+cvc4_add_unit_test_black(regexp_operation_black theory)
 cvc4_add_unit_test_black(theory_black theory)
 cvc4_add_unit_test_white(evaluator_white theory)
 cvc4_add_unit_test_white(logic_info_white theory)
diff --git a/test/unit/theory/regexp_operation_black.h b/test/unit/theory/regexp_operation_black.h
new file mode 100644
index 000000000..81f5cf34a
--- /dev/null
+++ b/test/unit/theory/regexp_operation_black.h
@@ -0,0 +1,152 @@
+/*********************                                                        */
+/*! \file regexp_operation_black.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andres Noetzli
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2019 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 Unit tests for symbolic regular expression operations
+ **
+ ** Unit tests for symbolic regular expression operations.
+ **/
+
+#include "expr/node.h"
+#include "expr/node_manager.h"
+#include "smt/smt_engine.h"
+#include "smt/smt_engine_scope.h"
+#include "theory/strings/regexp_operation.h"
+
+#include <cxxtest/TestSuite.h>
+#include <iostream>
+#include <memory>
+#include <vector>
+
+using namespace CVC4;
+using namespace CVC4::kind;
+using namespace CVC4::smt;
+using namespace CVC4::theory;
+using namespace CVC4::theory::strings;
+
+class RegexpOperationBlack : public CxxTest::TestSuite
+{
+ public:
+  RegexpOperationBlack() {}
+
+  void setUp() override
+  {
+    Options opts;
+    opts.setOutputLanguage(language::output::LANG_SMTLIB_V2);
+    d_em = new ExprManager(opts);
+    d_smt = new SmtEngine(d_em);
+    d_scope = new SmtScope(d_smt);
+    d_regExpOpr = new RegExpOpr();
+
+    d_nm = NodeManager::currentNM();
+  }
+
+  void tearDown() override
+  {
+    delete d_regExpOpr;
+    delete d_scope;
+    delete d_smt;
+    delete d_em;
+  }
+
+  void includes(Node r1, Node r2)
+  {
+    r1 = Rewriter::rewrite(r1);
+    r2 = Rewriter::rewrite(r2);
+    std::cout << r1 << " includes " << r2 << std::endl;
+    TS_ASSERT(d_regExpOpr->regExpIncludes(r1, r2));
+  }
+
+  void doesNotInclude(Node r1, Node r2)
+  {
+    r1 = Rewriter::rewrite(r1);
+    r2 = Rewriter::rewrite(r2);
+    std::cout << r1 << " does not include " << r2 << std::endl;
+    TS_ASSERT(!d_regExpOpr->regExpIncludes(r1, r2));
+  }
+
+  void testBasic()
+  {
+    Node sigma = d_nm->mkNode(REGEXP_SIGMA, std::vector<Node>{});
+    Node sigmaStar = d_nm->mkNode(REGEXP_STAR, sigma);
+    Node a = d_nm->mkNode(STRING_TO_REGEXP, d_nm->mkConst(String("a")));
+    Node c = d_nm->mkNode(STRING_TO_REGEXP, d_nm->mkConst(String("c")));
+    Node abc = d_nm->mkNode(STRING_TO_REGEXP, d_nm->mkConst(String("abc")));
+    Node sigma3 = d_nm->mkNode(REGEXP_CONCAT, sigma, sigma, sigma);
+    Node asc = d_nm->mkNode(REGEXP_CONCAT, a, sigma, c);
+    Node asw = d_nm->mkNode(REGEXP_CONCAT, a, sigma, sigmaStar);
+
+    includes(sigma3, abc);
+    doesNotInclude(abc, sigma3);
+
+    includes(sigma3, asc);
+    doesNotInclude(asc, sigma3);
+
+    includes(asc, abc);
+    doesNotInclude(abc, asc);
+
+    includes(asw, asc);
+    doesNotInclude(asc, asw);
+  }
+
+  void testStarWildcards()
+  {
+    Node sigma = d_nm->mkNode(REGEXP_SIGMA, std::vector<Node>{});
+    Node sigmaStar = d_nm->mkNode(REGEXP_STAR, sigma);
+    Node a = d_nm->mkNode(STRING_TO_REGEXP, d_nm->mkConst(String("a")));
+    Node c = d_nm->mkNode(STRING_TO_REGEXP, d_nm->mkConst(String("c")));
+    Node abc = d_nm->mkNode(STRING_TO_REGEXP, d_nm->mkConst(String("abc")));
+
+    Node _abc_ = d_nm->mkNode(REGEXP_CONCAT, sigmaStar, abc, sigmaStar);
+    Node _asc_ = d_nm->mkNode(REGEXP_CONCAT, sigmaStar, a, sigma, c, sigmaStar);
+    Node _sc_ = Rewriter::rewrite(
+        d_nm->mkNode(REGEXP_CONCAT, sigmaStar, sigma, c, sigmaStar));
+    Node _as_ = Rewriter::rewrite(
+        d_nm->mkNode(REGEXP_CONCAT, sigmaStar, a, sigma, sigmaStar));
+    Node _assc_ = d_nm->mkNode(
+        REGEXP_CONCAT,
+        std::vector<Node>{sigmaStar, a, sigma, sigma, c, sigmaStar});
+    Node _csa_ = d_nm->mkNode(REGEXP_CONCAT, sigmaStar, c, sigma, a, sigmaStar);
+    Node _c_a_ =
+        d_nm->mkNode(REGEXP_CONCAT, sigmaStar, c, sigmaStar, a, sigmaStar);
+    Node _s_s_ = Rewriter::rewrite(d_nm->mkNode(
+        REGEXP_CONCAT, sigmaStar, sigma, sigmaStar, sigma, sigmaStar));
+    Node _a_abc_ = Rewriter::rewrite(
+        d_nm->mkNode(REGEXP_CONCAT, sigmaStar, a, sigmaStar, abc, sigmaStar));
+
+    includes(_asc_, _abc_);
+    doesNotInclude(_abc_, _asc_);
+    doesNotInclude(_csa_, _abc_);
+    doesNotInclude(_assc_, _asc_);
+    doesNotInclude(_asc_, _assc_);
+    includes(_sc_, abc);
+    includes(_sc_, _abc_);
+    includes(_sc_, _asc_);
+    includes(_sc_, _assc_);
+    doesNotInclude(_sc_, _csa_);
+    includes(_as_, abc);
+    includes(_as_, _abc_);
+    includes(_as_, _asc_);
+    includes(_as_, _assc_);
+    doesNotInclude(_sc_, _csa_);
+    includes(_s_s_, _c_a_);
+    doesNotInclude(_c_a_, _s_s_);
+    includes(_abc_, _a_abc_);
+    doesNotInclude(_a_abc_, _abc_);
+  }
+
+ private:
+  ExprManager* d_em;
+  SmtEngine* d_smt;
+  SmtScope* d_scope;
+  RegExpOpr* d_regExpOpr;
+
+  NodeManager* d_nm;
+};