A Choice Machine as a formal specification of an automaton for semantics driven human-computer interaction and navigation as well as hypertext linking machine. This goes beyond Memex and Vannevar Bush's machine underlying the current Web and hypertext based systems.

Ontology Driven Query Languages as a new generation of query languages for semantic search on the Web as well as querying of databases and multimedia. This is an extension of my Ph.D. Thesis on MDDQL.

(Meta)Parsing techniques for natural language based querying via a controlled vocabulary. The technique exploits the parametric theory in linguistics as elaborated by N. Chomsky and his Ph.D. student M. Baker. It relies on the assumption of "languages having atoms" from which all natural languages emerge. The theory parallels with the theory of atoms and matter in Physics as well as the Periodic Table of Elements in Chemistry.

Context and Ontology based query translation as based on detection and exploitation of conceptual dependencies within cross-lingual queries. This contrasts with other query translation approaches as based on statistical methods and detection and exploitation of purely linguistic structures in a query.

Definition and construction of semantic (conceptual) multi-dimensional space models for measuring semantic distances among words in one or more than one natural language (multi-lingual index and mapping). This is based on Vector Space Models as well as other geometrical spaces (e.g., Manhattan).

Specification and construction of Semantic Metric Spaces for measuring quality of Aspect Oriented Programming and Software Development. The suite of metrics foresees symbolic and semantic based metrics for both code and design of software.

Collaborative Ontologies and Ontology Engineering, from both a methodology and theoretical point of view, as based on flexibility in accommodating various concerns and perspectives from involved user communities. The approach does not rely on the assumption of a common agreed upon domain ontology.