The *(term) for a variation on traditional _(graph reduction) where the availability of references obeys a _(linear logic) in its type. That is, only one object can refer to a specific expression/value unless a specific duplication combinator is used, in which case the outputs of the duplicator constitute two expressions with the same value in a sense.

About linear graph systems as _(object) frameworks, see _(Alan Bawden)'s _(thesis| ftp://publications.ai.mit.edu/ai-publications/1500-1999/AITR-1627.ps).