Slide: The One-Against-All Approach  break k-class problem into k binary problems and  solve each separately  say possible labels are Y = { , , , }  x1 x2 x3 x4 x5    x1 x2 x3 x4 x5      +  x1 x2 x3 x4 x5  +   +   x1 x2 x3 x4 x5   +     x1 x2 x3 x4 x5    +     to classify new example, choose label predicted to be most  positive   AdaBoost.MH  problem: not robust to errors in predictions [with Singer]
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