Communication system

LAN A conceptual diagram of a local area network. "LAN" redirects here. For other uses, see   LAN (disambiguation) . A   local area network   ( LAN ) is a   computer network   that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. [1]   By contrast, a   wide area network (WAN) not only covers a larger geographic distance, but also generally involves   leased telecommunication circuits . Ethernet   and   Wi-Fi   are the two most common technologies in use for local area networks. Historical technologies include   ARCNET , Token ring , and   AppleTalk . History Cabling Edit Early LAN cabling had generally been based on various grades of   coaxial cable . Shielded twisted pair   was used in IBM's   Token Ring LAN implementation, but in 1984,   StarLAN showed the potential of simple   unshielded twis...

Computer circuit A circuit is a triple   {\displaystyle (M,L,G)} , where {\displaystyle M}   is a set of values, {\displaystyle L}   is a set of gate labels, each of which is a function from   {\displaystyle M^{i}}   to   {\displaystyle M}   for some non-negative integer   {\displaystyle i}   (where   {\displaystyle i}   represents the number of inputs to the gate), and {\displaystyle G}   is a   labelled   directed acyclic graph with labels from   {\displaystyle L} . The vertices of the graph are called   gates . For each gate   {\displaystyle g}   of   in-degree   {\displaystyle i} , the gate   {\displaystyle g}   can be labeled by an element   {\displaystyle \ell }   of   {\displaystyle L}   if and only if   {\displaystyle \ell }   is defined on   {\displaystyle M^{i}} . Terminology Edit The gates of in-degree 0 are called ...