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A probabilistic framework for mismatch and profile string kernels. AbstractThere has recently been numerous applications of kernel methods in the field of bioinformatics. In particular, the problem of protein homology has served as a benchmark for the performance of many new kernels which operate directly on strings (such as amino-acid sequences). Several new kernels have been developed and successfully applied to this type of data, including spectrum, string, mismatch, and profile kernels. In this paper we introduce a general probabilistic framework for string kernels which uses the fisher-kernel approach and includes spectrum, mismatch and profile kernels, among others, as special cases. The use of a probabilistic model however provides additional flexibility both in definition and for the re-weighting of features through feature selection methods, prior knowledge or semi-supervised approaches which use data repositories such as BLAST. We give details of the framework and also give preliminary experimental results which show the applicability of the technique.
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