http://www.hongliangjie.com/publications/recsys2014.pdf

(t3 � t2) + (t5 � t4)

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t1 t2 t3 t4 t5

(t2 � t1) + (t5 � t4)

(t4 � t1)

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xq,d

xq,d = g(q,d)

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yq,d

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ft(x) = Tt(x;⇥) + �

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t=1

�tTt(x;⇥t)

L(yi, fT (xi))

Tt(x;⇥t)

⇥̂ = argmin�

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�t = argmin�

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L(yi, ft�1(xi) + �T (xi, ✓))

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i=1

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log2(i+ 1)

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MAP =

PUu=1 AveP (u)

U

AveP (u) =

PNk=1(P (k)⇥ rel(k))

# of relevant articles for user u

I =

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argminU,V

MX

i=1

X

ri,j<ri,k

Ui(Vj � Vk)T + �(|U |2 + |V |2)

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