{"project":[{"name":"International IST Postdoc Fellowship Programme","call_identifier":"FP7","_id":"25681D80-B435-11E9-9278-68D0E5697425","grant_number":"291734"},{"name":"Persistent Homology - Images, Data and Maps","call_identifier":"FP7","grant_number":"622033","_id":"255F06BE-B435-11E9-9278-68D0E5697425"}],"abstract":[{"text":"Bitmap images of arbitrary dimension may be formally perceived as unions of m-dimensional boxes aligned with respect to a rectangular grid in ℝm. Cohomology and homology groups are well known topological invariants of such sets. Cohomological operations, such as the cup product, provide higher-order algebraic topological invariants, especially important for digital images of dimension higher than 3. If such an operation is determined at the level of simplicial chains [see e.g. González-Díaz, Real, Homology, Homotopy Appl, 2003, 83-93], then it is effectively computable. However, decomposing a cubical complex into a simplicial one deleteriously affects the efficiency of such an approach. In order to avoid this overhead, a direct cubical approach was applied in [Pilarczyk, Real, Adv. Comput. Math., 2015, 253-275] for the cup product in cohomology, and implemented in the ChainCon software package [http://www.pawelpilarczyk.com/chaincon/]. We establish a formula for the Steenrod square operations [see Steenrod, Annals of Mathematics. Second Series, 1947, 290-320] directly at the level of cubical chains, and we prove the correctness of this formula. An implementation of this formula is programmed in C++ within the ChainCon software framework. We provide a few examples and discuss the effectiveness of this approach. One specific application follows from the fact that Steenrod squares yield tests for the topological extension problem: Can a given map A → Sd to a sphere Sd be extended to a given super-complex X of A? In particular, the ROB-SAT problem, which is to decide for a given function f: X → ℝm and a value r &gt; 0 whether every g: X → ℝm with ∥g - f ∥∞ ≤ r has a root, reduces to the extension problem.","lang":"eng"}],"scopus_import":1,"quality_controlled":"1","alternative_title":["LNCS"],"department":[{"_id":"UlWa"},{"_id":"HeEd"}],"intvolume":"      9667","citation":{"short":"M. Krcál, P. Pilarczyk, in:, Springer, 2016, pp. 140–151.","ama":"Krcál M, Pilarczyk P. Computation of cubical Steenrod squares. In: Vol 9667. Springer; 2016:140-151. doi:<a href=\"https://doi.org/10.1007/978-3-319-39441-1_13\">10.1007/978-3-319-39441-1_13</a>","ista":"Krcál M, Pilarczyk P. 2016. Computation of cubical Steenrod squares. CTIC: Computational Topology in Image Context, LNCS, vol. 9667, 140–151.","ieee":"M. Krcál and P. Pilarczyk, “Computation of cubical Steenrod squares,” presented at the CTIC: Computational Topology in Image Context, Marseille, France, 2016, vol. 9667, pp. 140–151.","apa":"Krcál, M., &#38; Pilarczyk, P. (2016). Computation of cubical Steenrod squares (Vol. 9667, pp. 140–151). Presented at the CTIC: Computational Topology in Image Context, Marseille, France: Springer. <a href=\"https://doi.org/10.1007/978-3-319-39441-1_13\">https://doi.org/10.1007/978-3-319-39441-1_13</a>","mla":"Krcál, Marek, and Pawel Pilarczyk. <i>Computation of Cubical Steenrod Squares</i>. Vol. 9667, Springer, 2016, pp. 140–51, doi:<a href=\"https://doi.org/10.1007/978-3-319-39441-1_13\">10.1007/978-3-319-39441-1_13</a>.","chicago":"Krcál, Marek, and Pawel Pilarczyk. “Computation of Cubical Steenrod Squares,” 9667:140–51. Springer, 2016. <a href=\"https://doi.org/10.1007/978-3-319-39441-1_13\">https://doi.org/10.1007/978-3-319-39441-1_13</a>."},"author":[{"first_name":"Marek","id":"33E21118-F248-11E8-B48F-1D18A9856A87","full_name":"Krcál, Marek","last_name":"Krcál"},{"first_name":"Pawel","id":"3768D56A-F248-11E8-B48F-1D18A9856A87","full_name":"Pilarczyk, Pawel","last_name":"Pilarczyk"}],"title":"Computation of cubical Steenrod squares","status":"public","ec_funded":1,"user_id":"3E5EF7F0-F248-11E8-B48F-1D18A9856A87","date_published":"2016-06-02T00:00:00Z","date_created":"2018-12-11T11:50:52Z","oa_version":"None","month":"06","type":"conference","_id":"1237","conference":{"start_date":"2016-06-15","location":"Marseille, France","name":"CTIC: Computational Topology in Image Context","end_date":"2016-06-17"},"date_updated":"2021-01-12T06:49:18Z","acknowledgement":"The research conducted by both authors has received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreements no. 291734 (for M. K.) and no. 622033 (for P. P.).","page":"140 - 151","publist_id":"6096","doi":"10.1007/978-3-319-39441-1_13","publication_status":"published","language":[{"iso":"eng"}],"day":"02","year":"2016","publisher":"Springer","volume":9667}