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diff --git a/src/decision/assertion_list.h b/src/decision/assertion_list.h
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+/******************************************************************************
+ * Top contributors (to current version):
+ *   Andrew Reynolds
+ *
+ * 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.
+ * ****************************************************************************
+ *
+ * Assertion list
+ */
+
+#include "cvc5_private.h"
+
+#ifndef CVC5__DECISION__ASSERTION_LIST_H
+#define CVC5__DECISION__ASSERTION_LIST_H
+
+#include <iosfwd>
+#include <unordered_set>
+#include <vector>
+
+#include "context/cdlist.h"
+#include "context/cdo.h"
+#include "expr/node.h"
+
+namespace cvc5 {
+namespace decision {
+
+/**
+ * For monitoring activity of assertions
+ */
+enum class DecisionStatus
+{
+  // not currently watching status of the current assertion
+  INACTIVE,
+  // no decision was made considering the assertion
+  NO_DECISION,
+  // a decision was made considering the assertion
+  DECISION,
+  // we backtracked while considering the assertion
+  BACKTRACK
+};
+const char* toString(DecisionStatus s);
+std::ostream& operator<<(std::ostream& out, DecisionStatus s);
+
+/**
+ * An assertion list used by the justification heuristic. This tracks a list
+ * of formulas that we must justify.
+ */
+class AssertionList
+{
+ public:
+  /**
+   * @param ac The context on which the assertions depends on. This is the
+   * user context for assertions. It is the SAT context for assertions that
+   * are dynamically relevant based on what is asserted, e.g. lemmas
+   * corresponding to skolem definitions.
+   * @param ic The context on which the current index of the assertions
+   * depends on. This is typically the SAT context.
+   * @param dyn Whether to use a dynamic ordering of the assertions. If this
+   * flag is true, then getNextAssertion will return the most important next
+   * assertion to consider based on heuristics in response to notifyStatus.
+   */
+  AssertionList(context::Context* ac,
+                context::Context* ic,
+                bool useDyn = false);
+  virtual ~AssertionList() {}
+  /** Presolve, which clears the dynamic assertion order */
+  void presolve();
+  /** Add the assertion n */
+  void addAssertion(TNode n);
+  /**
+   * Get the next assertion and increment d_assertionIndex.
+   */
+  TNode getNextAssertion();
+  /** Get the number of assertions */
+  size_t size() const;
+  /**
+   * Notify status, which indicates the status of the assertion n, where n
+   * is the assertion last returned by getNextAssertion above (independent of
+   * the context). The status s indicates what happened when we were trying to
+   * justify n. This impacts its order if useDyn is true.
+   */
+  void notifyStatus(TNode n, DecisionStatus s);
+
+ private:
+  /** The list of assertions */
+  context::CDList<Node> d_assertions;
+  /** The index of the next assertion to satify */
+  context::CDO<size_t> d_assertionIndex;
+  // --------------------------- dynamic assertions
+  /** are we using dynamic assertions? */
+  bool d_usingDynamic;
+  /** The list of assertions */
+  std::vector<TNode> d_dlist;
+  /** The set of assertions for fast membership testing in the above vector */
+  std::unordered_set<TNode, TNodeHashFunction> d_dlistSet;
+  /** The index of the next assertion to satify */
+  context::CDO<size_t> d_dindex;
+};
+
+}  // namespace decision
+}  // namespace cvc5
+
+#endif /* CVC5__DECISION__ASSERTION_LIST_H */