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A lossless or reversible steganography is defined as an original image can be completely recovered from the stego-image after the embedded data has been extracted. This technique has been focused on spatial uncompressed domain recently, and is considered more challenging to carry out in the compressed domain. In this paper, we propose a lossless, compressed domain steganography technique for AMBTC-compressed...
Distributed software systems are characterized by increasing autonomy. They often have the capability to sense the environment and react to it, discover the presence of other systems and take advantage of their services, adapt and re-configure themselves in accordance with the internal as well as the global state. Testing this kind of systems is challenging, and systematic and automated approaches...
This paper provides an overview of work being done in the EntryPoint project, which is examining the first course work in computing degrees. A key goal of this project is to move away from the traditional CS1/CS2 programming courses as the start of a computing degree. In addition, the project team is looking at how these ideas might be extended to BSSE degree programs. As such, this paper will discuss...
We develop fast parallel solutions to a number of basic problems involving solvable and nilpotent permutation groups. Testing solvability is in NC, and RNC includes, for solvable groups, finding order, testing membership, finding the derived series and finding a composition series. Additionally, for nilpotent groups, one can, in RNC, find the center, a central composition series, and point-wise stabilizers...
We prove a natural encoding scheme intractable (by showing it UR-complete, a technique which may be used when a problem does not yield to a proof of NP-completeness). This is the first non number-theoretic problem that is UR-complete but not known to be NP-complete. We also redefine UR-completeness (henceforth refered to as PR-completeness) in probabilistic terms thus making the notion conceptually...
This paper gives a personal account of some developments in automata theory and computational complexity theory. Though the account is subjective and deals primarily with the research areas of direct interest to the author, it discusses the underlying beliefs and philosophy which guided this research as well as the intellectual environment and the ideas and contacts which influenced it. An attempt...
We define alternating Turing Machines which are like nondeterministic Turing Machines, except that existential and universal quantifiers alternate. Alternation links up time and space complexities rather well, in that alternating polynomial time equals deterministic polynomial space, and alternating linear space equals deterministic exponential time. Such considerations lead to a two-person game complete...
Families of languages recognized by multi-head writing finite automata are considered. For n≥1, an n-head writing finite automaton (n-wfa) is a finite state device with n one-way read-write heads on a single input tape. Relationships between families of languages recognized by n-wfa (Wn) and other models (e.g. n-head nonwriting finite automata, linear-bounded automata, and real-time buffer automata)...
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