Quantifying the discord: Order discrepancies in message sequence charts

Edith Elkind, Blaise Genest, Doron Peled, Paola Spoletini

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Message Sequence Charts (MSCs) and High-level Message Sequence Charts (HMSCs) are formalisms used to describe scenarios of message passing protocols. We propose using Allen's logic to represent the temporal order of the messages. We introduce the concept of discord to quantify the discrepancies between the intuition and the semantics of the ordering between messages in different nodes of an HMSC. We study the algorithmic properties of this concept: we show that while the discord of a pair of messages is hard to compute in general, the problem becomes polynomial-time computable if the number of nodes of the HMSC or the number of processes is constant. Moreover, for a given HMSC, it is always computationally easy to identify a pair of messages that exhibits the worst-case discord and compute the discord of this pair.

Original languageEnglish
Pages (from-to)211-233
Number of pages23
JournalInternational Journal of Foundations of Computer Science
Issue number2
StatePublished - Apr 2010

Bibliographical note

Funding Information:
Part of this work was done when the fourth author was visiting Bar Ilan University and the first author was a Lady Davis Fellow at Hebrew University of Jerusalem. This research is partially supported by the ESF project Automatha, the ANR project DOTS, and an NRF Research Fellowship.


  • Discord
  • Message sequence charts
  • Order discrepancies


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