Comment on "On Siphon Computation for Deadlock Control in a Class of Petri Nets".

It was claimed recently in the paper by Li and Zhou that "a polynomial time algorithm for finding the set of elementary siphons in S³PRs is proposed, which avoids complete siphon enumeration." However, this is incorrect because Proposition 1 and Corollary 6 of the aforementioned paper, which lead to the claim, are both incorrect. In this correspondence paper, Proposition 1 and Corollary 6 are disproved. As a consequence, some claims of the aforesaid paper are denied. Two examples are presented to disprove some claims of the previously mentioned paper. [ABSTRACT FROM AUTHOR]