CPM's 20th Anniversary: A Statistical Retrospective

This year the Annual Symposium on Combinatorial Pattern Matching (CPM) celebrates its 20th anniversary. Over the last two decades the Symposium has established itself as the most recognized international forum for research in combinatorial pattern matching and related applications. Contributions to the conference typically address issues of searching and matching strings and more complex patterns such as trees, regular expressions, graphs, point sets, and arrays. Advances in this field rely on the ability to expose combinatorial properties of the computational problem at hand and to exploit these properties in order to either achieve superior performance or identify conditions under which searches cannot be performed efficiently. The meeting also deals with combinatorial problems in computational biology, data compression, data mining, coding, information retrieval, natural language processing and pattern recognition. The first edition of CPM was held in Paris in July 1990, and gathered about thirty participants. Since then the conference has been held every year, usually in June or July. Thirteen countries, over three continents, have hosted it (see Table 1). The “seed” of CPM can be traced back to a NATO-ASI Workshop in Maratea, Italy organized by Z. Galil and A. Apostolico. The volume collecting the contributions presented at the workshop [1] defined perhaps for the first time the scope of this research area, sometimes referred to as “stringology”. The intent of the first two editions of CPM was to reconnect with the participants and to the spirit of the NATO-ASI meeting in Maratea. CPM’90 and CPM’91 were organized like schools with neither submission/refereeing process nor proceedings. For CPM’92, however, NSF funding was contingent upon having a Program Committee and printed proceedings, so the Symposium was born. Selected papers from the 1990 meeting were published in a special issue of Theoretical Computer Science [2]. Since 1992, submitted papers have been peer-reviewed and accepted contributions have been published in Lecture Notes in Computer Science (Springer-Verlag). CPM proceedings have been published in the LNCS series, volumes 644 [8], 684 [9], 807 [10], 937 [11], 1075 [12], 1264 [13], 1448 [14], 1645 [15], 1848 [16], 2089 [17], 2373 [18], 2676 [19], 3109 [20], 3537 [21], 4009 [22], 4580 [23], and 5029 [24]. The practice of inviting a selected subset of the accepted papers for journal publication was resumed with the 11th meeting which appeared in volume 2 of Journal of Discrete Algorithms [5]. Then again, papers from the 12th meeting in volume 146 of Discrete Applied Mathematics [3], from the 14th meeting in volume 3 of Journal of