wip - adding proof checkers, fixes to quantifier proof certificates

src/sat/smt/tseitin_proof_checker.cpp

@@ -0,0 +1,78 @@
+/*++
+Copyright (c) 2022 Microsoft Corporation
+
+Module Name:
+
+    tseitin_proof_checker.cpp
+
+Abstract:
+
+    Plugin for checking quantifier instantiations
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2022-10-07
+
+
+--*/
+
+#include "sat/smt/tseitin_proof_checker.h"
+
+namespace tseitin {
+
+        
+    expr_ref_vector proof_checker::clause(app* jst) {
+        expr_ref_vector result(m);
+        result.append(jst->get_num_args(), jst->get_args());
+        return result;
+    }
+        
+    bool proof_checker::check(app* jst) {
+        expr* main_expr = nullptr;
+        unsigned max_depth = 0;
+        for (expr* arg : *jst) {
+            if (get_depth(arg) > max_depth) {
+                main_expr = arg;
+                max_depth = get_depth(arg);
+            }
+        }
+        if (!main_expr)
+            return false;
+
+        expr* a;
+        if (m.is_not(main_expr, a)) {
+            for (expr* arg : *jst)
+                if (equiv(a, arg))
+                    return true;
+            
+            if (m.is_and(a))
+                for (expr* arg1 : *to_app(a))
+                    for (expr* arg2 : *jst)
+                        if (equiv(arg1, arg2))
+                            return true;
+            
+            if (m.is_or(a))
+                return false;
+            if (m.is_implies(a))
+                return false;
+            if (m.is_eq(a))
+                return false;
+            if (m.is_ite(a))
+                return false;
+            if (m.is_distinct(a))
+                return false;
+        }
+        return false;
+    }
+
+    bool proof_checker::equiv(expr* a, expr* b) {
+        if (a == b)
+            return true;
+        expr* x, *y, *z, *u;
+        if (m.is_eq(a, x, y) && m.is_eq(b, z, u))
+            return x == u && y == z;
+        return false;
+    }
+
+
+}