by Mary Sarah Ruth Wilkin, Bishop's University

Formal grammars can be extended to explicitly model the notions of concurrency and parallelism. We examine one such an extension, namely the parallel communicating grammar system (PCGS) together with its different sub-types. We show how languages generated by a PCGS fall into the Chomsky hierarchy; however, we demonstrate that a PCGS can be far more powerful than a grammar of the same type. The available results related to the generative capacity and closure properties of the different types of PCGS are presented. We start with a discussion on the results for the most commonly studied subtypes, followed by results for the less common but arguably more interesting structural variations. We conclude with a presentation of open questions regarding the PCGS that we plan to examine moving forward. We plan to focus in particular on the existing contradiction surrounding the generative power of context-free PCGS, which were found to be either less powerful than context-sensitive grammars or Turing complete.

by Benjamin Teissier, Bishop's University

IT security is a complex and important field, having a long history. One of the oldest issues in this field is buffer overflow. This problem appeared early in the history of computers; indeed, buffer overflow is first mentioned as early as 1972, and the first documentation of a hostile exploitation was written in 1988 (though the exploitation of buffer overflows were present erlier, but some times documented privately and often not documented at all).

In its early history the exploitation of buffer overflows was reserved for the elite of hackers. However, the problem got out of communities and conventions and became available for the non-elite people with the famous paper “Smashing the stack for fun and profit,” written by Elias Levy (alias Aleph One) and published in the Phrack webzine in 1996. With this paper, the buffer overflow was popularized; additionally, a good and complete “how to” was made available to everyone. All of a sudden buffer overflow exploitation was made available to everybody, even to people without strong knowledge.

Buffer overflow is an old issue but at the same time it is a current and acute problem. We can see this by looking at the exploit-db.com Web site, a giant archive of exploits and vulnerable software: more than 100 pages (with some 20 articles per page) are dedicated to buffer overflows.

This talk presents the problem of buffer overflow and the solutions tried so far. We then propose our own potential solution. Our solution will be at the level of the kernel of the operating system, thus addressing the problem automatically for all the programs running on a machine.

For a 48-hour period that began at 5 p.m. Friday, September 28 and ended Sunday, September 30, the Department of Computer Science at Bishop’s became one of over 40 participating host universities and colleges of the Great Canadian Appathon 3, a nationwide competition organized by XMG Studio in partnership with The Globe and Mail and Electric Playground as well as a number of sponsors. At stake, some $30,000 in prizes and a chance to have a mobile game published. Read the full story.

The games designed by each of the 4 teams of Bishop's students will be presented during the seminar. The teams are:

• BUnique: Clément Michaud, Pierre Lukjanenko, Pauline Klein and Bryan Recinos
• RatJug: Jean-Christophe Charbonneau, Russell Butler, Geoffrey Guest and Tegan Maharaj
• J9: Eric Boisvert, Giuseppi Lupoi, Patrick Momo and Shixiao Zhan
• Peter Tosh: Jonas Bengtsson

Beside the main presentation short information sessions about the co-op programme (by Charlene Marion), the UCOSP (by Stefan Bruda), and the upcoming Hackfest (2-3 November, Quebec City) will take place.

Refreshments will be available.

If you are interested in getting real experience building a substantial software system as part of a distributed team, you'll be interested in UCOSP!

UCOSP is a senior undergraduate course, which has been running since September 2008. In this course, teams of students from several schools work together on an open-source software project. Each student registers in the appropriate course at his or her home institution (in our case this course would be either CSC 307 or CSC 308) and works in tandem with their peers from across the country. During one intensive weekend early in the course, students travel to meet face-to-face and work together.

This course exposes students to the tools, working practices, and issues that are now routine in global software development. Just as importantly, it enables them to get to know their peers from across the country. UCOSP is sponsored by Canadian CS Department Chairs and several industrial partners.

If you are interested in being involved, please contact Dr. Stefan D Bruda, who is the faculty partner for UCOSP at Bishop's.