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SUMMARY:Practical Linguistic Steganography using Contextual Synonym Substi
 tution and Vertex Colour Coding - Ching-Yun Chang and Stephen Clark\, Univ
 ersity of Cambridge
DTSTART:20101001T110000Z
DTEND:20101001T113000Z
UID:TALK26904@talks.cam.ac.uk
CONTACT:Thomas Lippincott
DESCRIPTION:Linguistic Steganography is concerned with hiding information 
 in natural language text. One of the major transformations used in Linguis
 tic Steganography is synonym substitution. However\, few existing studies 
 have studied the practical application of this approach. In this paper we 
 propose two improvements to the use of synonym substitution for encoding h
 idden bits of information. First\, we use the Web 1T Google n-gram corpus 
 for checking the applicability of a synonym in context\, and we evaluate t
 his method using data from the SemEval lexical substitution task. Second\,
  we address the problem that arises from words with more than one sense\, 
 which creates a potential ambiguity in terms of which bits are encoded by 
 a particular word. We develop a novel method in which words are the vertic
 es in a graph\, synonyms are linked by edges\, and the bits assigned to a 
 word are determined by a vertex colouring algorithm. This method ensures t
 hat each word encodes a unique sequence of bits\, without cutting out larg
 e number of synonyms\, and thus maintaining a reasonable embedding capacit
 y.\n
LOCATION:SW01\, Computer Laboratory
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