adding ack/model

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/sat/smt/euf_ackerman.h

@@ -0,0 +1,89 @@
+/*++
+Copyright (c) 2020 Microsoft Corporation
+
+Module Name:
+
+    euf_ackerman.h
+
+Abstract:
+
+    Ackerman reduction plugin for EUF
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2020-08-25
+
+--*/
+#pragma once
+
+#include "ast/euf/euf_egraph.h"
+#include "sat/smt/atom2bool_var.h"
+#include "sat/smt/sat_th.h"
+
+namespace euf {
+
+    class solver;
+
+    class ackerman {
+
+        struct inference {
+            bool is_cc;
+            expr* a, *b, *c;
+            inference* m_next{ nullptr };
+            inference* m_prev{ nullptr };
+            unsigned   m_count{ 0 };
+            inference():is_cc(false), a(nullptr), b(nullptr), c(nullptr) {}
+            inference(app* a, app* b):is_cc(true), a(a), b(b), c(nullptr) {}
+            inference(expr* a, expr* b, expr* c):is_cc(false), a(a), b(b), c(c) {}
+        };
+
+        struct inference_eq {
+            bool operator()(inference const* a, inference const* b) const {
+                return a->is_cc == b->is_cc && a->a == b->a && a->b == b->b && a->c == b->c;
+            }
+        };
+        
+        struct inference_hash {
+            unsigned operator()(inference const* a) const {
+                SASSERT(a->a && a->b);
+                return mk_mix(a->a->get_id(), a->b->get_id(), a->c ? a->c->get_id() : 0);
+            }
+        };
+
+        typedef hashtable<inference*, inference_hash, inference_eq> table_t;
+
+        solver&       s;
+        ast_manager&  m;
+        table_t       m_table;
+        inference*    m_queue { nullptr };
+        inference*    m_tmp_inference { nullptr };
+        unsigned      m_gc_threshold { 1 };
+        unsigned      m_propagate_threshold { 0 };
+        unsigned      m_num_propagations_since_last_gc { 0 };
+ 
+        void reset();
+        void new_tmp();
+        void insert(expr* a, expr* b, expr* lca);
+        void insert(app* a, app* b);
+        void insert();
+        void remove(inference* inf);
+        void add_cc(expr* a, expr* b);
+        void add_eq(expr* a, expr* b, expr* c);        
+        void gc();
+        void push_to_front(inference* inf);        
+        void remove_from_queue(inference* inf);
+
+    public:
+        ackerman(solver& s, ast_manager& m);
+        ~ackerman();
+
+        void cg_conflict_eh(expr * n1, expr * n2);
+                   
+        void used_eq_eh(expr* a, expr* b, expr* lca);
+        
+        void used_cc_eh(app* a, app* b);
+
+        void propagate();
+    };
+
+};