Euler calculus

From Wikipedia, the free encyclopedia
Jump to: navigation, search
For numerical analysis of ordinary differential equations, see Euler's method.

Euler calculus is a methodology from applied algebraic topology and integral geometry that integrates constructible functions and more recently definable functions[1] by integrating with respect to the Euler characteristic as a finitely-additive measure. In the presence of a metric, it can be extended to continuous integrands via the Gauss–Bonnet theorem.[2] It was introduced independently by Pierre Schapira[3][4][5] and Oleg Viro[6] in 1988, and is useful for enumeration problems in computational geometry and sensor networks.[7]

Euler integration for constructible functions[edit]

Euler calculus begins from the observation that the Euler characteristic obeys one of the main properties of a measure: . As a result, for a suitably restricted class of functions, it is possible to define an integral with respect to this measure. One begins by selecting an o-minimal structure of definable sets in the topology, for instance, semialgebraic or subanalytic sets. The class of constructible functions consists of those functions such that is definable for all . A definition of the Euler integral follows:

Due to the properties of the o-minimal structure, the integral may also be computed by decomposing as a sum of indicator functions defined on a disjoint union of cells (giving a cell structure). If , then

See also[edit]


  1. ^ Baryshnikov, Y.; Ghrist, R. Euler integration for definable functions, Proc. National Acad. Sci., 107(21), 9525–9530, 25 May 2010.
  2. ^ McTague, Carl (1 Nov 2015). "A New Approach to Euler Calculus for Continuous Integrands". arXiv:1511.00257free to read [math.DG]. 
  3. ^ Schapira, P. "Cycles Lagrangiens, fonctions constructibles et applications", Seminaire EDP, Publ. Ecole Polytechnique (1988/89)
  4. ^ Schapira, P. Operations on constructible functions, J. Pure Appl. Algebra 72, 1991, 83–93.
  5. ^ Schapira, Pierre. Tomography of constructible functions, Applied Algebra, Algebraic Algorithms and Error-Correcting Codes Lecture Notes in Computer Science, 1995, Volume 948/1995, 427–435, doi:10.1007/3-540-60114-7_33
  6. ^ Viro, O. Some integral calculus based on Euler characteristic, Lecture Notes in Math., vol. 1346, Springer-Verlag, 1988, 127–138.
  7. ^ Baryshnikov, Y.; Ghrist, R. Target enumeration via Euler characteristic integrals, SIAM J. Appl. Math., 70(3), 825–844, 2009.

External links[edit]

  • Ghrist, Robert. Euler Calculus video presentation, June 2009. published 30 July 2009.