Dear colleagues,
Next week Thu 20 Jan, from 11.00am, our colleague Susumu Nishimura from Dept. Math., Kyoto Univ. is making a talk on his recent work. No registration necessary. See you there!
Best regards, Ichiro Hasuo --- RIMS-CS website http://www.kurims.kyoto-u.ac.jp/~cs/
===== Speaker: Susumu Nishimura (Dept. Math., Kyoto Univ.)
Title: Calculating Tree Navigation with Symmetric Relational Zipper
Date: 11.00 - 12.00, Thursday 20 January 2011
Place: Room 478, "Research Bldg. No. 2 (Sougou Kenkyu 2-Goukan)" http://www.kyoto-u.ac.jp/en/access/campus/main.htm (Next to our CS Lab) 総合研究2号館 478号室 (CS室のとなりです) http://www.kyoto-u.ac.jp/ja/access/campus/map6r_y.htm
Abstract:
Navigating through tree structures is a core operation in tree processing programs. Most notably, XML processing programs intensively use XPath, the path specification language that locates particular nodes in a given document structure.
In this talk, a calculational method for deriving certain equalities of XPath expressions is presented. Tree navigation operations in XPath expressions, making the symmetries of those operations explicit. By exploiting the symmetry, certain equalities that are useful for optimizing XPath evaluation are derided by simple calculation. The point-free, algebraic reasoning on relations not only leads to a concise justification of some known results but also establishes equations over XPath expressions with negative predicates and those beyond XPath expressibility.
This is joint work with Yuta Ikeda.