Union (set theory)In set theory, the union (denoted by ∪) of a collection of sets is the set of all elements in the collection. It is one of the fundamental operations through which sets can be combined and related to each other. A refers to a union of zero () sets and it is by definition equal to the empty set. For explanation of the symbols used in this article, refer to the table of mathematical symbols. The union of two sets A and B is the set of elements which are in A, in B, or in both A and B.
Forwarding planeIn routing, the forwarding plane, sometimes called the data plane or user plane, defines the part of the router architecture that decides what to do with packets arriving on an inbound interface. Most commonly, it refers to a table in which the router looks up the destination address of the incoming packet and retrieves the information necessary to determine the path from the receiving element, through the internal forwarding fabric of the router, and to the proper outgoing interface(s).
Brick GothicBrick Gothic (Backsteingotik, Gotyk ceglany, Baksteengotiek) is a specific style of Gothic architecture common in Northeast and Central Europe especially in the regions in and around the Baltic Sea, which do not have resources of standing rock (though glacial boulders are sometimes available). The buildings are essentially built using bricks. Buildings classified as Brick Gothic (using a strict definition of the architectural style based on the geographic location) are found in Belgium (and the very north of France), Netherlands, Germany, Poland, Lithuania, Latvia, Estonia, Kaliningrad (former East Prussia), Denmark, Sweden and Finland.
