Technische Universität Berlin, Foschungsberichte des Fachbereichs Informatik No. 1989/23, 1989.
Abstract: The authors present several categorial constructions for Pteri nets which can be regarded as a suitable basis for composition and decompostion concepts. The authors show that the category of place/transition nets and the category of algebraic net schemes are cocomplete, ie that coproducts and cokernels exist. The T-invariant functor from the category of place/transition nets into the category of free abelian groups which assigns to each net its group of T-invariants preserves finite limits whereas the S-invariant functor transforms finite colimits into finite limits.
Keywords: categorial construction; composition; decomposition; place/transition net; algebraic net scheme; T-invariant; S-invariant; limit.