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_farkas_learner.h

@@ -0,0 +1,66 @@
+/*++
+Copyright (c) 2011 Microsoft Corporation
+
+Module Name:
+
+    spacer_farkas_learner.h
+
+Abstract:
+
+    SMT2 interface for the datalog SPACER
+
+Author:
+
+    Krystof Hoder (t-khoder) 2011-11-1.
+
+Revision History:
+
+--*/
+
+#ifndef _SPACER_FARKAS_LEARNER_H_
+#define _SPACER_FARKAS_LEARNER_H_
+
+#include "ast.h"
+
+namespace spacer {
+
+
+
+
+
+
+
+class farkas_learner {
+    typedef obj_hashtable<expr> expr_set;
+
+    bool m_split_literals;
+
+    void combine_constraints(unsigned cnt, app * const * constrs, rational const * coeffs, expr_ref& res);
+
+    bool is_farkas_lemma(ast_manager& m, expr* e);
+
+    void get_asserted(proof* p, expr_set const& bs, ast_mark& b_closed, obj_hashtable<expr>& lemma_set, expr_ref_vector& lemmas);
+
+    bool is_pure_expr(func_decl_set const& symbs, expr* e, ast_manager& m) const;
+
+public:
+    farkas_learner(): m_split_literals(false) {}
+
+    /**
+        Traverse a proof and retrieve lemmas using the vocabulary from bs.
+    */
+    void get_lemmas(proof* root, expr_set const& bs, expr_ref_vector& lemmas);
+
+    void collect_statistics(statistics& st) const {}
+    void reset_statistics() {}
+
+
+    /** \brief see smt::farkas_util::set_split_literals */
+    void set_split_literals(bool v) {m_split_literals = v;}
+
+};
+
+
+}
+
+#endif