25,146 research outputs found

    Learning a Pose Lexicon for Semantic Action Recognition

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    This paper presents a novel method for learning a pose lexicon comprising semantic poses defined by textual instructions and their associated visual poses defined by visual features. The proposed method simultaneously takes two input streams, semantic poses and visual pose candidates, and statistically learns a mapping between them to construct the lexicon. With the learned lexicon, action recognition can be cast as the problem of finding the maximum translation probability of a sequence of semantic poses given a stream of visual pose candidates. Experiments evaluating pre-trained and zero-shot action recognition conducted on MSRC-12 gesture and WorkoutSu-10 exercise datasets were used to verify the efficacy of the proposed method.Comment: Accepted by the 2016 IEEE International Conference on Multimedia and Expo (ICME 2016). 6 pages paper and 4 pages supplementary materia

    Space-Efficient Re-Pair Compression

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    Re-Pair is an effective grammar-based compression scheme achieving strong compression rates in practice. Let nn, σ\sigma, and dd be the text length, alphabet size, and dictionary size of the final grammar, respectively. In their original paper, the authors show how to compute the Re-Pair grammar in expected linear time and 5n+4σ2+4d+n5n + 4\sigma^2 + 4d + \sqrt{n} words of working space on top of the text. In this work, we propose two algorithms improving on the space of their original solution. Our model assumes a memory word of log2n\lceil\log_2 n\rceil bits and a re-writable input text composed by nn such words. Our first algorithm runs in expected O(n/ϵ)\mathcal O(n/\epsilon) time and uses (1+ϵ)n+n(1+\epsilon)n +\sqrt n words of space on top of the text for any parameter 0<ϵ10<\epsilon \leq 1 chosen in advance. Our second algorithm runs in expected O(nlogn)\mathcal O(n\log n) time and improves the space to n+nn +\sqrt n words

    A Systematic Approach to Identifying Protein-Ligand Binding Profiles on a Proteome Scale

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    Identification of protein-ligand interaction networks on a proteome scale is crucial to address a wide range of biological problems such as correlating molecular functions to physiological processes and designing safe and efficient therapeutics. We have developed a novel computational strategy to identify ligand binding profiles of proteins across gene families and applied it to predicting protein functions, elucidating molecular mechanisms of drug adverse effects, and repositioning safe pharmaceuticals to treat different diseases

    Subsequence Automata with Default Transitions

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    Let SS be a string of length nn with characters from an alphabet of size σ\sigma. The \emph{subsequence automaton} of SS (often called the \emph{directed acyclic subsequence graph}) is the minimal deterministic finite automaton accepting all subsequences of SS. A straightforward construction shows that the size (number of states and transitions) of the subsequence automaton is O(nσ)O(n\sigma) and that this bound is asymptotically optimal. In this paper, we consider subsequence automata with \emph{default transitions}, that is, special transitions to be taken only if none of the regular transitions match the current character, and which do not consume the current character. We show that with default transitions, much smaller subsequence automata are possible, and provide a full trade-off between the size of the automaton and the \emph{delay}, i.e., the maximum number of consecutive default transitions followed before consuming a character. Specifically, given any integer parameter kk, 1<kσ1 < k \leq \sigma, we present a subsequence automaton with default transitions of size O(nklogkσ)O(nk\log_{k}\sigma) and delay O(logkσ)O(\log_k \sigma). Hence, with k=2k = 2 we obtain an automaton of size O(nlogσ)O(n \log \sigma) and delay O(logσ)O(\log \sigma). On the other extreme, with k=σk = \sigma, we obtain an automaton of size O(nσ)O(n \sigma) and delay O(1)O(1), thus matching the bound for the standard subsequence automaton construction. Finally, we generalize the result to multiple strings. The key component of our result is a novel hierarchical automata construction of independent interest.Comment: Corrected typo
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