Quelle random.gi Sprache: unbekannt

#############################################################################
##
#F  RandomClosure( <G>, <fam>, <e> )
##
## <G>: group the nearring is acting on as a transformation nearring
## <fam>: the family of the elements of the nearring
## <e>: a record with the components
##  p : the result has probability 1/p to be incorrect
##  size : if the size of the nearring is known it can
##   be given to the function which produces a
##   correct result in this case
##
## Note: only one of p and size has to be set via the function
##  SetErrorProbability

RandomClosure := function ( group, fam, e )
local i, m, badp, p, size, addGens;

  if IsBound( e.size ) then
size := e.size;
p := 10^100;
  else
size := Size(fam!.group)^Size(fam!.group);
p := e.p;
  fi;

  Info( InfoNearRing, 2, "actual size: ",Size(group) );

  addGens := GeneratorsOfGroup( group );
  i := 0;
  badp := Length(addGens)/(Length(addGens)-1);
  while badp^i < p  and Size(group) < size do
#    Print("->",QuotientRemainder(NumeratorRat(badp^i),DenominatorRat(badp^i))[1],"\n");
    i := i + 1;
    Info( InfoNearRing, 2, "pass: ", i );
    m := GroupElementRepOfNearRingElement(
NearRingElementByGroupRep( fam, Random(group) ) *
NearRingElementByGroupRep( fam, Random( GeneratorsOfGroup(group) ) )
    );
    if not m in group then
return RandomClosure( ClosureGroup( group, m ), fam, e );
    fi;
  od;

  return group;
end;

#############################################################################
##
#M  GroupReduct( <TfmNR> )  random method
##

InstallMethod(
GroupReduct,
"random",
true,
[IsNearRing and IsTransformationNearRing and HasErrorProbability],
0,
  function ( nr )
  local addGroup, id;

  if ErrorProbability( nr ) = 0 then
TryNextMethod();
  fi;

  id := GroupElementRepOfNearRingElement( GeneratorsOfNearRing(nr)[1] )^0;
  addGroup := Group( List( GeneratorsOfNearRing(nr), GroupElementRepOfNearRingElement ), id );

  return RandomClosure( addGroup, nr!.elementsInfo, ErrorProbability( nr ) );
  end );

Quelle random.gi Sprache: unbekannt

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