Ontologies aim to represent what is general, by means of universal statements. In contrast, dispositional predications capture knowledge about what is likely to happen if a certain set of circumstances obtain, which is crucial in investigative research such as in drug discovery and systems biology, where entities which are constitutionally dissimilar can nevertheless have similar behavior in a biological context. While such dispositional properties are increasingly included in biomedical ontologies, the circumstances under which the dispositions are realized are seldom explicitly (...) modeled, and doing so is problematic due to the necessary restriction to binary relations in OWL ontologies. In this paper we address this shortcoming, focusing on the bioactivity of small molecules at varying levels of concentration within a living organism as our problem domain, although our approach is generalizable to other problems. We discuss the ontological nature and representation of dispositions and their realization; consider the nature of concentrations and their representation; and finally we detail an approach to linking dispositions to the conditions for their realization which regards conditions as triggers for the process in which the disposition is realized. (shrink)

Dispositions and tendencies feature significantly in the biomedical domain and therefore in representations of knowledge of that domain. They are not only important for specific applications like an infectious disease ontology, but also as part of a general strategy for modelling knowledge about molecular interactions. But the task of representing dispositions in some formal ontological systems is fraught with several problems, which are partly due to the fact that Description Logics can only deal well with binary relations. The paper will (...) discuss some of the results of the philosophical debate about dispositions, in order to see whether the formal relations needed to represent dispositions can be broken down to binary relations. Finally, we will discuss problems arising from the possibility of the absence of realizations, of multi-track or multi-trigger dispositions and offer suggestions on how to deal with them. (shrink)

BACKGROUND -/- In biomedical ontologies, mereological relations have always been subject to special interest due to their high relevance in structural descriptions of anatomical entities, cells, and biomolecules. This paper investigates two important subrelations of has_proper_part, viz. the relation has_grain, which relates a collective entity to its multiply occurring uniform parts (e.g., water molecules in a portion of water), and the relation has_component, which relates a compound to its constituents (e.g., molecules to the atoms they consist of). -/- METHOD -/- (...) We distinguish between four kinds of complex entities and characterize them in first order logic. We then discuss whether similar characterizations could be given in description logics, and finally apply the results to mixtures. -/- RESULTS -/- At first sight, collectives and compounds seem to be disjoint categories. Their disjointness, however, relies on agreement about what are uniform entities, and thus on the granularity of description. For instance, the distinction between isomeric subtypes of a molecule can be important in one use case but might be neglected in another one. We demonstrate that, as implemented in the BioTop domain upper level ontology, equivalence or subsumption between different descriptions of same or similar entities cannot be achieved. Using OWL-DL, we propose a new design pattern that avoids primitive subrelations at the expense of more complex descriptions and thus supports the needed inferences. (shrink)