shared ( T , T ′  ) = 1 2  ∑ v ∈ T   ∑ v ′  ∈ T ′    shared ( v , v ′  )       MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=vr0dc8meaabaqaciaacaGaaeqabaqabeGadaaakeaacqqGZbWCcqqGObaAcqqGHbqycqqGYbGCcqqGLbqzcqqGKbazcqGGOaakcqWGubavcqGGSaalcuWGubavgaqbaiabcMcaPiabg2da9maalaaabaGaeGymaedabaGaeGOmaidaamaaqafabaWaaabuaeaacqqGZbWCcqqGObaAcqqGHbqycqqGYbGCcqqGLbqzcqqGKbazcqGGOaakcqWG2bGDcqGGSaalcuWG2bGDgaqbaiabcMcaPaWcbaGafmODayNbauaacqGHiiIZcuWGubavgaqbaaqab0GaeyyeIuoaaSqaaiabdAha2jabgIGiolabdsfaubqab0GaeyyeIuoaaaa@570E@