Spacer engine for HORN logic

The algorithms implemented in the engine are described in the following papers

Anvesh Komuravelli, Nikolaj Bjørner, Arie Gurfinkel, Kenneth L. McMillan:
Compositional Verification of Procedural Programs using Horn Clauses over Integers and Arrays. FMCAD 2015: 89-96

Nikolaj Bjørner, Arie Gurfinkel:
Property Directed Polyhedral Abstraction. VMCAI 2015: 263-281

Anvesh Komuravelli, Arie Gurfinkel, Sagar Chaki:
SMT-Based Model Checking for Recursive Programs. CAV 2014: 17-34

src/muz/spacer/spacer_generalizers.h

@@ -0,0 +1,99 @@
+/*++
+Copyright (c) 2017 Microsoft Corporation and Arie Gurfinkel
+
+Module Name:
+
+    spacer_generalizers.h
+
+Abstract:
+
+    Generalizer plugins.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2011-11-22.
+    Arie Gurfinkel
+Revision History:
+
+--*/
+
+#ifndef _SPACER_GENERALIZERS_H_
+#define _SPACER_GENERALIZERS_H_
+
+#include "spacer_context.h"
+#include "arith_decl_plugin.h"
+
+namespace spacer {
+
+// can be used to check whether produced core is really implied by
+// frame and therefore valid TODO: or negation?
+class lemma_sanity_checker : public lemma_generalizer {
+public:
+    lemma_sanity_checker(context& ctx) : lemma_generalizer(ctx) {}
+    virtual ~lemma_sanity_checker() {}
+    virtual void operator()(lemma_ref &lemma);
+};
+
+/**
+ * Boolean inductive generalization by dropping literals
+ */
+class lemma_bool_inductive_generalizer : public lemma_generalizer {
+
+    struct stats {
+        unsigned count;
+        unsigned num_failures;
+        stopwatch watch;
+        stats() {reset();}
+        void reset() {count = 0; num_failures = 0; watch.reset();}
+    };
+
+    unsigned m_failure_limit;
+    stats m_st;
+
+public:
+    lemma_bool_inductive_generalizer(context& ctx, unsigned failure_limit) :
+        lemma_generalizer(ctx), m_failure_limit(failure_limit) {}
+    virtual ~lemma_bool_inductive_generalizer() {}
+    virtual void operator()(lemma_ref &lemma);
+
+    virtual void collect_statistics(statistics& st) const;
+    virtual void reset_statistics() {m_st.reset();}
+};
+
+class unsat_core_generalizer : public lemma_generalizer {
+    struct stats {
+        unsigned count;
+        unsigned num_failures;
+        stopwatch watch;
+        stats() { reset(); }
+        void reset() {count = 0; num_failures = 0; watch.reset();}
+    };
+
+    stats m_st;
+public:
+    unsat_core_generalizer(context &ctx) : lemma_generalizer(ctx) {}
+    virtual ~unsat_core_generalizer() {}
+    virtual void operator()(lemma_ref &lemma);
+
+    virtual void collect_statistics(statistics &st) const;
+    virtual void reset_statistics() {m_st.reset();}
+};
+
+class lemma_array_eq_generalizer : public lemma_generalizer {
+public:
+    lemma_array_eq_generalizer(context &ctx) : lemma_generalizer(ctx) {}
+    virtual ~lemma_array_eq_generalizer() {}
+    virtual void operator()(lemma_ref &lemma);
+
+};
+
+class lemma_eq_generalizer : public lemma_generalizer {
+public:
+    lemma_eq_generalizer(context &ctx) : lemma_generalizer(ctx) {}
+    virtual ~lemma_eq_generalizer() {}
+    virtual void operator()(lemma_ref &lemma);
+};
+
+
+};
+#endif