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Presentation - MIV

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collet@lsiit.u-strasbg.fr<br />

iAstro Workshop - Nice Observatory<br />

16/17 October 2003<br />

Hughe phenomenon<br />

Inherent sparsity of high dimensional spaces<br />

* in the absence of simplifying assumptions, the amount of data needed<br />

to get reasonably low variance estimators is really high<br />

* N-band observations >> N times more data but in R N space<br />

Dimensionality reduction<br />

* appropriate dimensionality of the reduced feature space<br />

* Important structure in the data actually lies in a much smaller<br />

dimensional space, and will therefore try to reduce the<br />

dimensionality before attempting the classification.<br />

This approach can be successful if the dimensionality reduction/feature<br />

extraction method loses as little relevant information as possible in the<br />

transformation from high-dimensional space to the low-dimensional one.

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