L CE = − log P(+|w, c pos ) k i=1 P(−|w, c neg i ) = − log P(+|w, c pos ) + k i=1 log P(−|w, c neg i ) = − log P(+|w, c pos ) + k i=1 log 1 − P(+|w, c neg i ) = − log σ (c pos • w) + k i=1 log σ (−c neg i • w) (6.34)