Tensor products of weakly smooth codes are robust

Abstract

We continue the study of robust tensor codes and expand the class of base codes that can be used as a starting point for the construction of locally testable codes via robust two-wise tensor products. In particular, we show that all unique-neighbor expander codes and all locally correctable codes, when tensored with any other good-distance code, are robust and hence can be used to construct locally testable codes. Previous works by [2] required stronger expansion properties to obtain locally testable codes. Our proofs follow by defining the notion of weakly smooth codes that generalize the smooth codes of [2]. We show that weakly smooth codes are sufficient for constructing robust tensor codes. Using the weaker definition, we are able to expand the family of base codes to include the aforementioned ones. © 2008 Springer-Verlag Berlin Heidelberg.