#
# This example demonstrates intersections.  An intersection is a logical and of
# roles or osets.  An intersection succeeds if the principal is in the
# intersection of the sets defined by the roles.
#
# The policy set by Acme is that a character must both a preferred customer and
# a WarnerBrothers character to buy rockets.  Each of those attributes is
# specified by a role.
#
# This example defines 4 principals, Acme, WarnerBrothers, Coyote and Batman.
# Credential 1 defines the policy requiring both roles to get the buy_rockets
# role.  Credential 2 gives the Coyote a preferred_customer role.  Credential 3
# gives Batman the preferred_customer role and Credential 4 recognizes the
# Coyote as a Warner Brothers character.
#
#In order to buy rockets from Acme, you must be BOTH a preferred customer
#AND a WarnerBros character. In this example, the following query will be
#successful:
#
#    Acme.buy_rockets <-?- Coyote
#
#The following query will fail (because Batman does not have the
#attribute WarnerBros.character):
#
#    Acme.buy_rockets <-?- Batman
# 
# Acme.buy_rockets <- Acme.preferred_customer & WarnerBros.character
# Acme.preferred_customer <- Coyote
# Acme.preferred_customer <- Batman
# WarnerBros.character <- Coyote