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Probing the h-core: an investigation of the tail–core ratio for rank distributions


The set of citations received by a set of publications consists of citations received by articles in the h-core and citations received by articles in the h-tail. Denoting the cardinalities of these fours sets as C, P, C H and C T we introduce the tail-core ratio (C T/C H) and show that in practical cases this ratio tends to increase. Introducing further the k-index, defined as k = (C/P)/(C T/C H), we show that this index decreases in most practical cases. A power law model is in accordance with these practical observations.

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Fred Y. Ye’s work is supported by a grant from the National Natural Science Foundation of China (NSFC Grant No. 70773101), while Ronald Rousseau’s work is supported by the National Natural Science Foundation of China Grant No. 70673019. The authors thank graduate student Jianhui Tang for assistance in data collection and Leo Egghe for checking the power law calculations.

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Correspondence to Ronald Rousseau.

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Ye, F.Y., Rousseau, R. Probing the h-core: an investigation of the tail–core ratio for rank distributions. Scientometrics 84, 431–439 (2010).

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  • h-Index
  • h-Core
  • h-Tail
  • Tail–core ratio
  • v-Index
  • k-Index