License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
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DOI: 10.4230/LIPIcs.CCC.2016.29
URN: urn:nbn:de:0030-drops-58438
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Gurjar, Rohit ; Korwar, Arpita ; Saxena, Nitin

Identity Testing for Constant-Width, and Commutative, Read-Once Oblivious ABPs

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We give improved hitting-sets for two special cases of Read-once Oblivious Arithmetic Branching Programs (ROABP). First is the case of an ROABP with known variable order. The best hitting-set known for this case had cost (nw)^{O(log(n))}, where n is the number of variables and w is the width of the ROABP. Even for a constant-width ROABP, nothing better than a quasi-polynomial bound was known. We improve the hitting-set complexity for the known-order case to n^{O(log(w))}. In particular, this gives the first polynomial time hitting-set for constant-width ROABP (known-order). However, our hitting-set works only over those fields whose characteristic is zero or large enough. To construct the hitting-set, we use the concept of the rank of partial derivative matrix. Unlike previous approaches whose starting point is a monomial map, we use a polynomial map directly.

The second case we consider is that of commutative ROABP. The best known hitting-set for this case had cost d^{O(log(w))}(nw)^{O(log(log(w)))}, where d is the individual degree. We improve this hitting-set complexity to (ndw)^{O(log(log(w)))}. We get this by achieving rank concentration more efficiently.

BibTeX - Entry

  author =	{Rohit Gurjar and Arpita Korwar and Nitin Saxena},
  title =	{{Identity Testing for Constant-Width, and Commutative, Read-Once Oblivious ABPs}},
  booktitle =	{31st Conference on Computational Complexity (CCC 2016)},
  pages =	{29:1--29:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-008-8},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{50},
  editor =	{Ran Raz},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-58438},
  doi =		{10.4230/LIPIcs.CCC.2016.29},
  annote =	{Keywords: PIT, hitting-set, constant-width ROABPs, commutative ROABPs}

Keywords: PIT, hitting-set, constant-width ROABPs, commutative ROABPs
Collection: 31st Conference on Computational Complexity (CCC 2016)
Issue Date: 2016
Date of publication: 19.05.2016

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