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closure

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closure


  3  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Closure  \Clo"sure\  (?,  135),  n.  [Of.  closure,  L.  clausura,  fr 
  clauedere  to  shut.  See  {Close},  v.  t.] 
  1.  The  act  of  shutting;  a  closing;  as  the  closure  of  a 
  chink. 
 
  2.  That  which  closes  or  shuts;  that  by  which  separate  parts 
  are  fastened  or  closed. 
 
  Without  a  seal,  wafer,  or  any  closure  whatever. 
  --Pope. 
 
  3.  That  which  incloses  or  confines;  an  inclosure. 
 
  O  thou  bloody  prison  .  .  .  Within  the  guilty  closure 
  of  thy  walls  Richard  the  Second  here  was  hacked  to 
  death.  --Shak. 
 
  4.  A  conclusion;  an  end  [Obs.]  --Shak. 
 
  5.  (Parliamentary  Practice)  A  method  of  putting  an  end  to 
  debate  and  securing  an  immediate  vote  upon  a  measure 
  before  a  legislative  body.  It  is  similar  in  effect  to  the 
  previous  question.  It  was  first  introduced  into  the 
  British  House  of  Commons  in  1882.  The  French  word 
  {cl[^o]ture}  was  originally  applied  to  this  proceeding. 
 
  From  WordNet  r  1.6  [wn]: 
 
  closure 
  n  1:  approaching  a  particular  destination;  a  coming  closer;  a 
  narrowing  of  a  gap;  "the  ship's  rapid  rate  of  closing 
  gave  them  little  time  to  avoid  a  collision"  [syn:  {closing}] 
  2:  a  rule  for  ending  debate  in  a  deliberative  body  [syn:  {cloture}, 
  {gag  rule}] 
  3:  an  obstruction  in  a  pipe  or  tube;  "we  had  to  call  a  plumber 
  to  clear  out  the  blockage  in  the  drainpipe"  [syn:  {blockage}, 
  {block},  {occlusion},  {stop},  {stoppage}] 
  4:  the  act  of  blocking  [syn:  {blockage},  {occlusion}] 
  5:  termination  of  operations  [syn:  {closedown},  {closing},  {shutdown}] 
  v  :  terminate  and  take  a  vote;  "Closure  a  debate"  [syn:  {cloture}] 
 
  From  The  Free  On-line  Dictionary  of  Computing  (13  Mar  01)  [foldoc]: 
 
  closure 
 
  1.    In  a  {reduction  system},  a  closure  is  a  data 
  structure  that  holds  an  expression  and  an  environment  of 
  variable  bindings  in  which  that  expression  is  to  be  evaluated. 
  The  variables  may  be  local  or  global.  Closures  are  used  to 
  represent  unevaluated  expressions  when  implementing 
  {functional  programming  languages}  with  {lazy  evaluation}.  In 
  a  real  implementation,  both  expression  and  environment  are 
  represented  by  pointers. 
 
  A  {suspension}  is  a  closure  which  includes  a  flag  to  say 
  whether  or  not  it  has  been  evaluated.  The  term  "{thunk}"  has 
  come  to  be  synonymous  with  closure"  but  originated  outside 
  {functional  programming}. 
 
  2.    In  {domain  theory},  given  a  {partially  ordered 
  set},  D  and  a  subset,  X  of  D,  the  upward  closure  of  X  in  D  is 
  the  union  over  all  x  in  X  of  the  sets  of  all  d  in  D  such  that 
  x  <=  d.  Thus  the  upward  closure  of  X  in  D  contains  the 
  elements  of  X  and  any  greater  element  of  D.  A  set  is  "upward 
  closed"  if  it  is  the  same  as  its  upward  closure,  i.e.  any  d 
  greater  than  an  element  is  also  an  element.  The  downward 
  closure  (or  "left  closure")  is  similar  but  with  d  <=  x.  A 
  downward  closed  set  is  one  for  which  any  d  less  than  an 
  element  is  also  an  element. 
 
  ("<="  is  written  in  {LaTeX}  as  {\subseteq}  and  the  upward 
  closure  of  X  in  D  is  written  \uparrow_\{D}  X). 
 
  (1994-12-16) 
 
 




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