--- /dev/null
+(* Copyright (C) 2000, HELM Team.
+ *
+ * This file is part of HELM, an Hypertextual, Electronic
+ * Library of Mathematics, developed at the Computer Science
+ * Department, University of Bologna, Italy.
+ *
+ * HELM is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * HELM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with HELM; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ *
+ * For details, see the HELM World-Wide-Web page,
+ * http://cs.unibo.it/helm/.
+ *)
+
+(* This module implements the Query interface to the Coercion Graph *)
+
+type coercion_search_result =
+ | SomeCoercion of Cic.term
+ | NoCoercion
+ | NotMetaClosed
+ | NotHandled of string Lazy.t
+
+val look_for_coercion :
+ Cic.term -> Cic.term -> coercion_search_result
+
+val is_a_coercion: Cic.term -> bool
+val source_of: Cic.term -> Cic.term
+val target_of: Cic.term -> Cic.term
+