602 research outputs found
Information Masking and Amplification: The Source Coding Setting
The complementary problems of masking and amplifying channel state
information in the Gel'fand-Pinsker channel have recently been solved by Merhav
and Shamai, and Kim et al., respectively. In this paper, we study a related
source coding problem. Specifically, we consider the two-encoder source coding
setting where one source is to be amplified, while the other source is to be
masked. In general, there is a tension between these two objectives which is
characterized by the amplification-masking tradeoff. In this paper, we give a
single-letter description of this tradeoff.
We apply this result, together with a recent theorem by Courtade and Weissman
on multiterminal source coding, to solve a fundamental entropy characterization
problem.Comment: 6 pages, 1 figure, to appear at the IEEE 2012 International Symposium
on Information Theory (ISIT 2012
Compressing Sparse Sequences under Local Decodability Constraints
We consider a variable-length source coding problem subject to local
decodability constraints. In particular, we investigate the blocklength scaling
behavior attainable by encodings of -sparse binary sequences, under the
constraint that any source bit can be correctly decoded upon probing at most
codeword bits. We consider both adaptive and non-adaptive access models,
and derive upper and lower bounds that often coincide up to constant factors.
Notably, such a characterization for the fixed-blocklength analog of our
problem remains unknown, despite considerable research over the last three
decades. Connections to communication complexity are also briefly discussed.Comment: 8 pages, 1 figure. First five pages to appear in 2015 International
Symposium on Information Theory. This version contains supplementary materia
Do Read Errors Matter for Genome Assembly?
While most current high-throughput DNA sequencing technologies generate short
reads with low error rates, emerging sequencing technologies generate long
reads with high error rates. A basic question of interest is the tradeoff
between read length and error rate in terms of the information needed for the
perfect assembly of the genome. Using an adversarial erasure error model, we
make progress on this problem by establishing a critical read length, as a
function of the genome and the error rate, above which perfect assembly is
guaranteed. For several real genomes, including those from the GAGE dataset, we
verify that this critical read length is not significantly greater than the
read length required for perfect assembly from reads without errors.Comment: Submitted to ISIT 201
Coded Cooperative Data Exchange for a Secret Key
We consider a coded cooperative data exchange problem with the goal of
generating a secret key. Specifically, we investigate the number of public
transmissions required for a set of clients to agree on a secret key with
probability one, subject to the constraint that it remains private from an
eavesdropper.
Although the problems are closely related, we prove that secret key
generation with fewest number of linear transmissions is NP-hard, while it is
known that the analogous problem in traditional cooperative data exchange can
be solved in polynomial time. In doing this, we completely characterize the
best possible performance of linear coding schemes, and also prove that linear
codes can be strictly suboptimal. Finally, we extend the single-key results to
characterize the minimum number of public transmissions required to generate a
desired integer number of statistically independent secret keys.Comment: Full version of a paper that appeared at ISIT 2014. 19 pages, 2
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