Well Constructed Workflows in Bioinformatics

We demonstrate and discuss the advantages of bioinformatical workflows which have no side-effects over those which do have them. In particular, we describe a method to give a formal, mathematical semantics to the side-effect-free workflows defined in SCUFL, the workflo w definition language of Taverna. This is achieved by translating them into a natural extension of the Nested Relational Calculus NRC.