Author:
Börger Egon,Kleine Büning Hans
Reference9 articles.
1. Private communication. December 1977.
2. and , Petri nets and commutative grammars. Laboratorio di Calcolatori. Rapporto interno N. 74–5.
3. Decision problems for Petri nets and vector addition systems. Com.-Structures Group, Memo 95, Project MAC, MIT.
4. Recursive Unsolvability of Post's Problem of "Tag" and other Topics in Theory of Turing Machines