fixes to bugs exposed by regressions

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

src/ast/rewriter/pb_rewriter.cpp

@@ -0,0 +1,65 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    pb_rewriter.cpp
+
+Abstract:
+
+    Basic rewriting rules for PB constraints.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2013-14-12
+
+Notes:
+
+--*/
+
+#include "pb_rewriter.h"
+
+br_status pb_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result) {
+    ast_manager& m = result.get_manager();
+    rational sum(0), maxsum(0);
+    for (unsigned i = 0; i < num_args; ++i) {
+        if (m.is_true(args[i])) {
+            sum += m_util.get_coeff(f, i);
+            maxsum += m_util.get_coeff(f, i);
+        }
+        else if (!m.is_false(args[i])) {
+            maxsum += m_util.get_coeff(f, i);            
+        }
+    }
+    rational k = m_util.get_k(f);
+    
+    switch(f->get_decl_kind()) {
+    case OP_AT_MOST_K:
+    case OP_PB_LE:
+        if (sum > k) {
+            result = m.mk_false();
+            return BR_DONE;
+        }
+        if (maxsum <= k) {
+            result = m.mk_true();
+            return BR_DONE;
+        }
+        return BR_FAILED;
+    case OP_AT_LEAST_K:
+    case OP_PB_GE:
+        if (sum >= k) {
+            result = m.mk_true();
+            return BR_DONE;
+        }
+        if (maxsum < k) {
+            result = m.mk_false();
+            return BR_DONE;
+        }
+        return BR_FAILED;
+    default:
+        UNREACHABLE();
+        return BR_FAILED;
+    }    
+}
+
+