= ( 1 − p i k   ) ( 1 − p j k   )   i f  x i k   = 0   a n d  x j k   = 0    P ( x i k   , x j k   )   = p i k   ( 1 − p j k   )   i f  x i k   ≠ 0   a n d  x j k   = 0    = ( 1 − p i k   ) p j k     i f  x i k   = 0   a n d  x j k   ≠ 0    = p i k   p j k   d ( x i k   , x j k   ) ( 2 N k  − d ( x i k   , x j k   ) − 1 )  N k  ( N k  − 1 )     i f  x i k   ≠ 0   a n d  x j k   ≠ 0           ( 2 )    MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=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fgaHjab=5gaUjab=rgaKjab=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@F695@