[logic-ml] Talk by Susumu Nishimura, Thursday next week (20 Jan)

[Ichiro Hasuo]

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/


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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.