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Some embodiments provide a method for using headerspace analysis. The method receives several flow entries for dis tribution to a forwarding element in a network. Each flow entry includes a set of conditions to be matched by a packet header and a set of actions to perform on a packet that matches the set of conditions. The method models each of the flow entries as a function that operates on a representa tion of a packet header. The method determines a set of packet headers of packets to be received by the forwarding element. The method determines a set of the flow entries that are not matched by a packet header of any packet to be received by the forwarding element by applying the func tions to representations of the identified set of packet head ers.