%I Springer %X We study behavioural relations for process algebra with a fluid semantics given in terms of a system of ordinary differential equations (ODEs). We introduce label equivalence, a relation which is shown to induce an exactly lumped fluid model, a potentially smaller ODE system which can be exactly related to the original one. We show that, in general, for two processes that are related in the fluid sense nothing can be said about their relationship from stochastic viewpoint. However, we identify a class of models for which label equivalence implies a correspondence, called semi-isomorphism, between their transition systems that are at the basis of the Markovian interpretation. %P 380-394 %T Exact fluid lumpability for Markovian process algebra %K Stochastic process algebra; ordinary differential equations; equivalence relations %B CONCUR 2012 ? Concurrency Theory %O 23rd International Conference, CONCUR 2012, Newcastle upon Tyne, UK, September 4-7, 2012. Proceedings %R 10.1007/978-3-642-32940-1_27 %S Lecture Notes in Computer Science %D 2012 %A Max Tschaikowski %A Mirco Tribastone %N 7454 %L eprints2587