Context and ontology in understanding of dialogs

We present a model of NLP in which ontology and context are directly included in a grammar. The model is based on the concept of {\em construction}, consisting of a set of features of form, a set of semantic and pragmatic conditions describing its application context, and a description of its meaning. In this model ontology is embedded into the grammar; e.g. the hierarchy of {\it np} constructions is based on the corresponding ontology. Ontology is also used in defining contextual parameters; e.g. $\left[ current\_question \ time(\_) \right]$. A parser based on this model allowed us to build a set of dialog understanding systems that include an on-line calendar, a banking machine, and an insurance quote system. The proposed approach is an alternative to the standard "pipeline" design of morphology-syntax-semantics-pragmatics; the account of meaning conforms to our intuitions about compositionality, but there is no homomorphism from syntax to semantics.