Irregular Recovery and Unequal Locality for Locally Recoverable Codes with Availability (1705.05005v1)

Abstract: A code is said to be a Locally Recoverable Code (LRC) with availability if every coordinate can be recovered from multiple disjoint sets of other coordinates called recovering sets. The vector of sizes of recovering sets of a coordinate is called its recovery profile. In this work, we consider LRCs with availability under two different settings: (1) irregular recovery: non-constant recovery profile that remains fixed for all coordinates, (2) unequal locality: regular recovery profile that can vary with coordinates. For each setting, we derive bounds for the minimum distance that generalize previously known bounds to the cases of irregular or varying recovery profiles. For the case of regular and fixed recovery profile, we show that a specific Tamo-Barg polynomial-evaluation construction is optimal for all-symbol locality, and we provide parity-check matrix constructions for information locality with availability.