A computer-implemented method for identifying multiword expressions in an input string, comprising: morphologically analyzing words of the input string including assigning word senses to the words to identify their alternative base forms and parts of speech without disambiguating words in the input string, thereby keeping all possible word senses as alternative paths in a first finite-state network; using the analyzed words of the input string to compile the input string into the first finite-state network; matching the first finite-state network with a second finite-state network of multiword expressions being a transducer with subnets 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 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; characterized in that said first finite-state network is an automaton that is not minimized with respect to the number of states in the first finite-state network; said morphological analysis is performed without segmenting the input string into sentences to permit multiword expressions to span multiple sentences; and further characterized by maintaining the order of arcs in the first finite-state network used to identify the derivative form of the input string; maintaining the order of morphological variants for each word in the first finite-state network in order to maintain the correct sense indices for the words in the input string after being morphologically analyzed, wherein the sense index of a word is based on the order in which different analyses of the words are produced during morphological analysis; and maintaining the order of states and transitions in the first finite-state network consistent with: (a) the order of the words in the input string; and (b) the order in which word senses are assigned during morphological analysis. morphologically analyzing words of the input string including assigning word senses to the words to identify their alternative base forms and parts of speech without disambiguating words in the input string, thereby keeping all possible word senses as alternative paths in a first finite-state network; using the analyzed words of the input string to compile the input string into the first finite-state network; matching the first finite-state network with a second finite-state network of multiword expressions being a transducer with subnets 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 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; characterized in that said first finite-state network is an automaton that is not minimized with respect to the number of states in the first finite-state network; said morphological analysis is performed without segmenting the input string into sentences to permit multiword expressions to span multiple sentences; and further characterized by maintaining the order of arcs in the first finite-state network used to identify the derivative form of the input string; maintaining the order of morphological variants for each word in the first finite-state network in order to maintain the correct sense indices for the words in the input string after being morphologically analyzed, wherein the sense index of a word is based on the order in which different analyses of the words are produced during morphological analysis; and maintaining the order of states and transitions in the first finite-state network consistent with: (a) the order of the words in the input string; and (b) the order in which word senses are assigned during morphological analysis. (a) the order of the words in the input string; and (b) the order in which word senses are assigned during morphological analysis.