1. A method for identifying multiword expressions in an input string, comprising: morphologically analyzing words of the input string to identify their alternative base forms and parts of speech; using the analyzed words of the input string to compile the input string into a first finite-state network; matching the first finite-state network with a second finite-state network of multiword expressions to identify all subpaths of the first finite-state network that match one or more complete paths in the second finite-state network; each matching subpath of the first finite-state network and path of the second finite-state network identifying a multiword expression in the input string; wherein said morphological analysis is performed without disambiguating words in the input string to compile the first finite-state network with at least one path that identifies alternative base forms or parts of speech of a word in the input string.