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Your search keyword '"Khachatryan, Andranik"' showing total 18 results
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18 results on '"Khachatryan, Andranik"'

1. Optimal alphabet for single text compression

Author

Allahverdyan, Armen E. and Khachatryan, Andranik

Subjects
Computer Science - Information Theory, Computer Science - Computation and Language, Physics - Data Analysis, Statistics and Probability
Abstract

A text written using symbols from a given alphabet can be compressed using the Huffman code, which minimizes the length of the encoded text. It is necessary, however, to employ a text-specific codebook, i.e. the symbol-codeword dictionary, to decode the original text. Thus, the compression performance should be evaluated by the full code length, i.e. the length of the encoded text plus the length of the codebook. We studied several alphabets for compressing texts -- letters, n-grams of letters, syllables, words, and phrases. If only sufficiently short texts are retained, an alphabet of letters or two-grams of letters is optimal. For the majority of Project Gutenberg texts, the best alphabet (the one that minimizes the full code length) is given by syllables or words, depending on the representation of the codebook. Letter 3 and 4-grams, having on average comparable length to syllables/words, perform noticeably worse than syllables or words. Word 2-grams also are never the best alphabet, on the account of having a very large codebook. We also show that the codebook representation is important -- switching from a naive representation to a compact one significantly improves the matters for alphabets with large number of symbols, most notably the words. Thus, meaning-expressing elements of the language (syllables or words) provide the best compression alphabet., Comment: 17 pages, 14 figures, 2 table; enlarged and clarified version

Published
2022

5. Magnetic Studies of Iron-Doped Probable Weyl Semimetal WTe2

Author

Khachatryan, Andranik S., primary, Charnaya, Elena V., additional, Likholetova, Marina V., additional, Shevchenko, Evgeniy V., additional, Lee, Min Kai, additional, Chang, Lieh-Jeng, additional, Naumov, Sergey V., additional, Perevalova, Alexandra N., additional, Marchenkova, Elena B., additional, and Marchenkov, Vyacheslav V., additional

Published
2023
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8. Sensitivity of Self-tuning Histograms: Query Order Affecting Accuracy and Robustness

Author

Khachatryan, Andranik, Müller, Emmanuel, Stier, Christian, Böhm, Klemens, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Ailamaki, Anastasia, editor, and Bowers, Shawn, editor

Published
2012
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9. Efficient Selectivity Estimation by Histogram Construction Based on Subspace Clustering

Author

Khachatryan, Andranik, Müller, Emmanuel, Böhm, Klemens, Kopper, Jonida, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Bayard Cushing, Judith, editor, French, James, editor, and Bowers, Shawn, editor

Published
2011
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11. Accurate Cost Estimation Using Distribution-Based Cardinality Estimates for Multi-dimensional Queries

Author

Khachatryan, Andranik, Böhm, Klemens, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Bayard Cushing, Judith, editor, French, James, editor, and Bowers, Shawn, editor

Published
2011
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13. Clustering-Initialized Adaptive Histograms and Probabilistic Cost Estimation for Query Optimization

Author

Khachatryan, Andranik and Böhm, K.

Subjects
DATA processing & computer science, ddc:004
Abstract

An assumption with self-tuning histograms has been that they can "learn" the dataset if given enough training queries. We show that this is not the case with the current approaches. The quality of the histogram depends on the initial configuration. Starting with few good buckets can improve the efficiency of learning. Without this, the histogram is likely to stagnate, i.e. converge to a bad configuration and stop learning. We also present a probabilistic cost estimation model.

Published
2012

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