Published by the Department of Computer Science, The University of Chicago.
and
Tom Gur
Department of Electrical Engineering and Computer Science
University of California, Berkeley
Berkeley, CA, USA
tom DOT gur AT berkeley DOT edu
We initiate a study of ``universal locally testable codes" (ULTCs). These codes admit local tests for membership in numerous possible subcodes, allowing for testing properties of the encoded message. More precisely, a ULTC $C:\{0,1\}^k \to \{0,1\}^n$ for a family of functions $\mathcal{F} = \left\{ f_i : \{0,1\}^k \to \{0,1\} \right\}_{i \in [M]}$ is a code such that for every $i \in [M]$ the subcode $\{ C(x) \: : \: f_i(x) = 1 \}$ is locally testable. We show a ``canonical" $O(1)$-local ULTC of length $\tilde O(M\cdot s)$ for any family $\mathcal{F}$ of $M$ functions such that every $f\in\mathcal{F}$ can be computed by a circuit of size $s$, and establish a lower bound of the form $n=M^{1/O(k)}$, which can be strengthened to $n=M^{\Omega(1)}$ for any $\mathcal{F}$ such that every $f,f' \in\mathcal{F}$ disagree on a constant fraction of their domain.
Submitted June 2, 2017, revised June 20, 2018,
published August 7, 2018.