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# 1990 noun classification from predicate argument

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Unformatted text preview: Posi-ve Pointwise Mutual Informa-on (PPMI) is common 62 Dan Jurafsky Pointwise Mutual Informa1on •  Pointwise mutual informa1on: •  Do events x and y co ­occur more than if they were independent? PMI( X, Y ) = log 2 P( x, y) P ( x )P ( y ) •  PMI between two words: (Church & Hanks 1989) •  Do words x and y co ­occur more than if they were independent? PMI(word1, word2 ) = log 2 P(word1,word2 ) P(word1)P(word2 ) •  Posi1ve PMI between two words (Niwa & Nina 1994) •  Replace all PMI values less than 0 with zero Dan Jurafsky Compu1ng PPMI on a term ­context matrix •  Matrix F with W rows (words) and C columns (contexts) •  fij is # of -mes wi occurs in context cj W C pij = fij WC !! fij pi* = i=1 j =1 64 ! fij ! fij p pmiij = log 2 ij pi* p* j j =1 WC p* j = !! fij i=1 j =1 i=1 WC !! fij i=1 j =1 ! pmi # ij ppmiij = " #0 \$ if pmiij > 0 otherwise Dan Jurafsky pij = fij WC !! fij i=1 j =1 W C ! fij ! fij p(w=informa-on,c=data) = 6/19 = .32 p(wi ) = j=1 11/19 = .58 p(w=informa-on) = N p(c=data) = 7/19 = .37 !"#\$%&'()*(+ !"#\$%&'( *\$(+!"& 1211 \$+,'*\$\$/' 1211 )+0+&*/ 1244 +,6"(#*&+", 1213 65 )*&* 1211 1211 1213 1275 !"%&'()*(+ 127: 1249 \$+,!- ('.%/& 1213 1211 1213 1211 1211 1213 1211 1254 1244 1259 p( c j ) = i=1 N !"#+ .%0*( 1213 1213 1211 1211 1244 1244 1244 1254 1238 Dan Jurafsky pij pmiij = log 2 pi* p* j !"#\$%&'( *\$(+!"& 1211 \$+,'*\$\$/' 1211 )+0+&*/ 1244 +,6"(#*&+", 1213 !"%&'()*(+ 1249 !"#\$%&'()*(+ )*&* \$+,!- ('.%/& 1211 1213 1211 1211 1213 1211 1213 1211 1213 1275 1211 1254 127: 1244 1259 !"#+ .%0*( 1213 1213...
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