∑ i  ∑ j  ∑ k ≠ i   ∑ l ≠ j   | F i  ∩ G j  | | F i  ∩ G l  | | F k  ∩ G l  | | F k  ∩ G j  |               ( 9 )    MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=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@6C97@