title: Notions of similarity for systems biology models.
abstract: Systems biology models are rapidly increasing in complexity, size and numbers. When building large models, researchers rely on software tools for the retrieval, comparison, combination and merging of models, as well as for version control. These tools need to be able to quantify the differences and similarities between computational models. However, depending on the specific application, the notion of 'similarity' may greatly vary. A general notion of model similarity, applicable to various types of models, is still missing. Here we survey existing methods for the comparison of models, introduce quantitative measures for model similarity, and discuss potential applications of combined similarity measures. To frame model comparison as a general problem, we describe a theoretical approach to defining and computing similarities based on a combination of different model aspects. The six aspects that we define as potentially relevant for similarity are underlying encoding, references to biological entities, quantitative behaviour, qualitative behaviour, mathematical equations and parameters and network structure. We argue that future similarity measures will benefit from combining these model aspects in flexible, problem-specific ways to mimic users' intuition about model similarity, and to support complex model searches in databases.
authors.forename: Ron
authors.initials: R
authors.lastname: Henkel
authors.forename: Robert
authors.initials: R
authors.lastname: Hoehndorf
authors.forename: Tim
authors.initials: T
authors.lastname: Kacprowski
authors.forename: Christian
authors.initials: C
authors.lastname: Knüpfer
authors.forename: Wolfram
authors.initials: W
authors.lastname: Liebermeister
authors.forename: Dagmar
authors.initials: D
authors.lastname: Waltemath
mesh_terms: D000818:Animals; D019295:Computational Biology / Q000379:methods*; D003198:Computer Simulation; D016208:Databases, Factual; D006801:Humans; D008954:Models, Biological; D015398:Signal Transduction; D012984:Software; D049490:Systems Biology / Q000379:methods*; D014584:User-Computer Interface
keywords: SBML; information retrieval; model version control; network model; systems biology