Topic Modeling 历些毛子种枝大学 XIDIAN UNIVERSITY ▣pLSI Model One layer of 'Deep Neutral Network' ▣Assumption p(w[=) p(z d) p(d) Pairs(d,w)are assumed to be generated independently W Conditioned on z,w is generated independently of d W2 Words in a document are exchangeable Documents are exchangeable WN Latent topics z are independent The generative process Multinomial Distribution p(d,w)=p(wld)p(d)=p(d)(w,=d)=p(d)(p(=d) Multinomial Distribution 2016/1229 9 Software Engineering2016/12/29 Software Engineering Topic Modeling 9 pLSI Model w1 w2 wN z1 zK z2 d1 d2 dM ….. ….. ….. p(w | z) p(z | d) p(d)  Assumption  Pairs(d,w) are assumed to be generated independently  Conditioned on z, w is generated independently of d  Words in a document are exchangeable  Documents are exchangeable  Latent topics z are independent The generative process ∑ z∈Z ∑ z∈Z p(d,w) = p(w| d) p(d) = p(d) p(w,z | d) = p(d) p(w| z) p(z | d) Multinomial Distribution Multinomial Distribution One layer of ‘Deep Neutral Network’