deletions | additions       diff --git a/However_several_difficulties_are_inherent__.tex b/However_several_difficulties_are_inherent__.tex  index 71c794b..6233a7a 100644  --- a/However_several_difficulties_are_inherent__.tex  +++ b/However_several_difficulties_are_inherent__.tex 
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However several difficulties are inherent to Several issues arise when dealing with  the clustering problem. First of all all,  the result of the clustering of a data points set process  is deeply strongly  related to the metric used. Then chosen metric. Second,  clustering algorithm used to be extremely algorithms are usually  sensitive to out layers and initialization and initialization. Therefore,  it might be difficult to determine automatically the best number of clusters which is most of the time an input of the clustering algorithm.