11,542 research outputs found
Unavoidable Multicoloured Families of Configurations
Balogh and Bollob\'as [{\em Combinatorica 25, 2005}] prove that for any
there is a constant such that any set system with at least sets
reduces to a -star, an -costar or an -chain. They proved
. Here we improve it to for some constant
.
This is a special case of the following result on the multi-coloured
forbidden configurations at 2 colours. Let be given. Then there exists a
constant so that a matrix with entries drawn from with
at least different columns will have a submatrix that
can have its rows and columns permuted so that in the resulting matrix will be
either or (for some ), where
is the matrix with 's on the diagonal and 's else
where, the matrix with 's below the diagonal and
's elsewhere. We also extend to considering the bound on the number of
distinct columns, given that the number of rows is , when avoiding a matrix obtained by taking any one of the matrices above
and repeating each column times. We use Ramsey Theory.Comment: 16 pages, add two application
Existence of Good Sweepouts on Closed Manifolds
In this note we establish estimates for the harmonic map heat flow from
into a closed manifold, and use it to construct sweepouts with the following
good property: each curve in the tightened sweepout, whose energy is close to
the maximal energy of curves in the sweepout, is itself close to a closed
geodesic.Comment: 7 pages; added reference; corrected typo
A Covert Data Transport Protocol
Both enterprise and national firewalls filter network connections. For data
forensics and botnet removal applications, it is important to establish the
information source. In this paper, we describe a data transport layer which
allows a client to transfer encrypted data that provides no discernible
information regarding the data source. We use a domain generation algorithm
(DGA) to encode AES encrypted data into domain names that current tools are
unable to reliably differentiate from valid domain names. The domain names are
registered using (free) dynamic DNS services. The data transmission format is
not vulnerable to Deep Packet Inspection (DPI).Comment: 8 pages, 10 figures, conferenc
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