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TianZheng3Oct2018
(01 Oct 2018,
ThomasStewart
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%HEAD{ NAME="Tian Zheng, !PhD" AFFILIATION="Columbia University" TITLE=" Boosted Sparse Non-linear Distance Metric Learning" IMAGELINK="http://www.stat.columbia.edu/~tzheng/files/IMG_0802a.JPG" }% Distance measures have been used as natural measures of (dis)similarity and served as the foundation of various learning methods. The efficiency of distance-based learning methods heavily depends on the chosen distance metric. With increasing dimensionality and complexity of data, however, traditional metric learning methods suffer from poor scalability and the limitation due to linearity as the true signals are usually embedded within a low-dimensional nonlinear subspace. In this talk, I will present a nonlinear sparse metric learning algorithm via boosting. It restructures a global optimization problem into a forward stage-wise learning of weak learners based on a rank-one decomposition of the weight matrix in the Mahalanobis distance metric. A gradient boosting algorithm is devised to obtain a sparse rank-one update of the weight matrix at each step. Nonlinear features are learned by a hierarchical expansion of interactions incorporated within the boosting algorithm. Meanwhile, an early stopping rule is imposed to control the overall complexity of the learned metric. As a result, our approach guarantees three desirable properties of the final metric: positive semi-definiteness, low rank and element-wise sparsity. Numerical experiments show that our learning model compares favorably with the state-of-the-art methods in the current literature of metric learning. <br> <br> %TAIL{DATE="3 October 2018"}% <!-- * Set HEAD = <div class="w3-card-2" id="task" style="max-width:750px; margin-left: 0px;"> <header class="w3-container w3-blue" style="padding:40px"><h1>Biostatistics Weekly Seminar</h1><br><h2 style="color:white;">%TITLE%<br><br>%NAME%<br>%AFFILIATION%</h2></header><div class="w3-container" style="padding:40px"><IMG SRC=%IMAGELINK% align="left" id="mug"/> * Set TAIL = <br><h3>MRBIII, Room 1220<br>%DATE%<br>1:30pm</h3></div></div><br>[[%TOPIC%Itinerary][Speaker Itinerary]] --> <style> .w3-card-2,.w3-example{box-shadow:0 2px 4px 0 rgba(0,0,0,0.16),0 2px 10px 0 rgba(0,0,0,0.12)!important} .w3-blue,.w3-hover-blue:hover{color:#fff!important;background-color:#2196F3!important} .w3-container{padding:0.01em 16px} .foswikiTopic {font-family: 'Open Sans', sans-serif;} /* Removes location hierarchy (usually written in grey text) */ .patternHomePath {display:none;} /* Removes bar with edit and attach buttons and location hierarchy */ .patternTop{display:none;} h1, h2, h3, h4, h5, h6{font-family: 'Montserrat','Open Sans', sans-serif;font-weight:700;} h1, h2, h3, h4, h5, h6{color:#bf1735;} h1:first-of-type{color:#2a3e6e;margin-bottom:25px;margin-top:5px;} .foswikiImage{margin-left:-9px;} img#mug{padding-right: 40px; padding-bottom:25px; height:250px;} </style>
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Topic revision: r4 - 01 Oct 2018,
ThomasStewart
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