1. A system comprising at least one processor configured to form: a computer-implemented lexicon manager configured to receive a multiword lexicon entry for a multiword expression of a natural language, wherein the multiword lexicon entry comprises Grammar Abstract Language (GAL) code describing a dependency tree comprising a plurality of nodes, the GAL code describing an attribute-value tree for each dependency tree node, and in response to displaying a graphical representation of the dependency tree on a computer-implemented display device, receive a user input indicating a modification of the dependency tree, and determine an edited lexicon entry according to the multiword lexicon entry and the modification, wherein the edited lexicon entry comprises GAL code, and wherein the display device is configured to receive user input indicating modifications of the dependency tree including a dependency tree node creation, a dependency tree node deletion, an inter-node link creation, an inter-node link deletion, a modification of a type of inter-node link, and a textual annotation of a dependency tree node; and a GAL compiler connected to the lexicon manager and configured to compile the GAL code representing the edited lexicon entry into Extensible Markup Language (XML) code.