2 research outputs found
Near-Linear Time Insertion-Deletion Codes and (1+)-Approximating Edit Distance via Indexing
We introduce fast-decodable indexing schemes for edit distance which can be
used to speed up edit distance computations to near-linear time if one of the
strings is indexed by an indexing string . In particular, for every length
and every , one can in near linear time construct a string
with , such that, indexing
any string , symbol-by-symbol, with results in a string where for which edit
distance computations are easy, i.e., one can compute a
-approximation of the edit distance between and any other
string in time.
Our indexing schemes can be used to improve the decoding complexity of
state-of-the-art error correcting codes for insertions and deletions. In
particular, they lead to near-linear time decoding algorithms for the
insertion-deletion codes of [Haeupler, Shahrasbi; STOC `17] and faster decoding
algorithms for list-decodable insertion-deletion codes of [Haeupler, Shahrasbi,
Sudan; ICALP `18]. Interestingly, the latter codes are a crucial ingredient in
the construction of fast-decodable indexing schemes
Random-Self-Reducibility
We consider Arthur-Merlin proof systems where (a) Arthur is a probabilistic quasi-polynomial time Turing machine, denoted AMqpoly, and (b) Arthur is a probabilistic exponential time Turing machine, denoted AMexp. We prove two new results related to these classes.- We show that if co-NP is in AMqpoly then the exponential hierarchy collapses to AMexp.- We show that if SAT is polylogarithmic round adaptive random-self-reducible, then SAT is in AMqpoly with a polynomial advice. The first result improves a recent result of Selman and Sengupta (2004) who showed that the hypothesis collapses the exponential hierarchy to S exp 2.PNP; a complexity class which contains AMexp. The second result implies that if SAT is polylogarithmic round adaptive random-selfreducible, then the exponential hierarchy collapses. This partially answers a question posed by Feigenbaum and Fortnow (1993) who showed that if SAT is logarithmic round adaptive random-self-reducible then the polynomial hierarchy collapses.