...final principal set...
(pAcme,keyid,y) 
(pCoyote,keyid,y) 

...final policy attribute set...
pAcme.buy_rockets <- pAcme.preferred_customer
pAcme.buy_rockets <- pAcme.worst_lucked
pAcme.preferred_customer <- pCoyote
pAcme.worst_lucked <- pCoyote

===good============ Acme.buy_rockets <- Coyote
YAP query succeed
pAcme.buy_rockets <- pAcme.preferred_customer
pAcme.preferred_customer <- pCoyote

next proof:
pAcme.buy_rockets <- pAcme.worst_lucked
pAcme.worst_lucked <- pCoyote
no more..


===good============ Acme.preferred_customer <- Coyote
YAP query succeed
pAcme.preferred_customer <- pCoyote

next proof:
no more..


===bad=============== Coyote.friend <- Acme
YAP query failed

next proof:
no more..