49 research outputs found
Interference Automata
We propose a computing model, the Two-Way Optical Interference Automata
(2OIA), that makes use of the phenomenon of optical interference. We introduce
this model to investigate the increase in power, in terms of language
recognition, of a classical Deterministic Finite Automaton (DFA) when endowed
with the facility of optical interference. The question is in the spirit of
Two-Way Finite Automata With Quantum and Classical States (2QCFA) [A. Ambainis
and J. Watrous, Two-way Finite Automata With Quantum and Classical States,
Theoretical Computer Science, 287 (1), 299-311, (2002)] wherein the classical
DFA is augmented with a quantum component of constant size. We test the power
of 2OIA against the languages mentioned in the above paper. We give efficient
2OIA algorithms to recognize languages for which 2QCFA machines have been shown
to exist, as well as languages whose status vis-a-vis 2QCFA has been posed as
open questions. Finally we show the existence of a language that cannot be
recognized by a 2OIA but can be recognized by an space Turing machine.Comment: 19 pages. A preliminary version appears under the title "On a Model
of Computation based on Optical Interference" in Proc. of the 16-th
Australasian Workshop on Combinatorial Algorithms (AWOCA'05), pp. 249-26
Statistical Model Checking for Cops and Robbers Game on Random Graph Models
Cops and robbers problem has been studied over the decades with many variants and
applications in graph searching problem. In this work, we study a variant of cops and
robbers problem on graphs. In this variant, there are di�erent types of cops and a
minimum number of each type of cops are required to catch a robber. We studied this
model over various random graph models and analyzed the properties using statistical
model checking.
To the best of our knowledge this variant of the cops and robber problem has
not been studied yet. We have used statistical techniques to estimate the probability
of robber getting caught in di�erent random graph models. We seek to compare
the ease of catching robbers performing random walk on graphs, especially complex
networks. In this work, we report the experiments that yields interesting empirical
results. Through the experiments we have observed that it is easier to catch a robber
in Barab�asi Albert model than in Erd�os-R�enyi graph model. We have also experimented
with k-Regular graphs and real street networks.
In our work, the model is framed as the multi-agent based system and we have implemented
a statistical model checker, SMCA tool which veri�es agents based systems
using statistical techniques. SMCA tool can take the model in JAVA programming
language and support Probabilistic - Bounded LTL logic for property specification
Towards Communication-Efficient Quantum Oblivious Key Distribution
Oblivious Transfer, a fundamental problem in the field of secure multi-party
computation is defined as follows: A database DB of N bits held by Bob is
queried by a user Alice who is interested in the bit DB_b in such a way that
(1) Alice learns DB_b and only DB_b and (2) Bob does not learn anything about
Alice's choice b. While solutions to this problem in the classical domain rely
largely on unproven computational complexity theoretic assumptions, it is also
known that perfect solutions that guarantee both database and user privacy are
impossible in the quantum domain. Jakobi et al. [Phys. Rev. A, 83(2), 022301,
Feb 2011] proposed a protocol for Oblivious Transfer using well known QKD
techniques to establish an Oblivious Key to solve this problem. Their solution
provided a good degree of database and user privacy (using physical principles
like impossibility of perfectly distinguishing non-orthogonal quantum states
and the impossibility of superluminal communication) while being loss-resistant
and implementable with commercial QKD devices (due to the use of SARG04).
However, their Quantum Oblivious Key Distribution (QOKD) protocol requires a
communication complexity of O(N log N). Since modern databases can be extremely
large, it is important to reduce this communication as much as possible. In
this paper, we first suggest a modification of their protocol wherein the
number of qubits that need to be exchanged is reduced to O(N). A subsequent
generalization reduces the quantum communication complexity even further in
such a way that only a few hundred qubits are needed to be transferred even for
very large databases.Comment: 7 page
Rare occurrence of sunfish Mola mola (Linnaeus) from the coastal waters off Visakhapatnam (Bay of Bengal)
The occurrence of sunfish in any sea is a
rare event. It is so rare that even fishermen
engaged in fishing throughout their lives find
it totally strange when they come across one.
On 6 May, 1986, a local fisherman reported
to the Zoology Department of the Andhra
University that a very strange looking fish was
part of that day's catch
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