Guided Parsing of Range Concatenation Languages 
 The theoretical study of the range concatenation grammar [RCG] formalism has revealed many attractive properties which may be used in NLP . In particular, range concatenation languages [RCL] can be parsed in polynomial time and many classical grammatical formalisms can be translated into equivalent RCGs without increasing their worst-case parsing time complexity . For example, after translation into an equivalent RCG , any tree adjoining grammar can be parsed in O(n6) time . In this paper, we study a parsing technique whose purpose is to improve the practical efficiency of RCL parsers . The non-deterministic parsing choices of the main parser for a language L are directed by a guide which uses the shared derivation forest output by a prior RCL parser for a suitable superset of L . The results of a practical evaluation of this method on a wide coverage English grammar are given. 