/// <summary>
/// Petrick's method (https://en.wikipedia.org/wiki/Petrick%27s_method) is too complicated for lab work programming.
/// Thats why lets implement primitive method based on teacher's explanation.
/// </summary>
private static List <Implicant> GetMinimalDisjunctionNormalForm(List <Implicant> constituents, List <Implicant> implicants)
{
var coreImplicants = new HashSet <Implicant>();
foreach (Implicant implicant in implicants)
{
foreach (Implicant constituent in constituents)
{
List <Implicant> implicantsInConstituent = implicants.Where(i => i.IsSubsetOf(constituent)).ToList();
if (implicantsInConstituent.Count == 1 && implicantsInConstituent.Contains(implicant))
{
coreImplicants.Add(implicant);
continue;
}
}
}
List <Implicant> noncoreImplicants = implicants.Except(coreImplicants).ToList();
List <Implicant> notCoveredConstituents = constituents
.Where(c => !coreImplicants.Any(coreImplicant => coreImplicant.IsSubsetOf(c))).ToList();
List <Implicant> resultImplicants = coreImplicants.ToList();
while (notCoveredConstituents.Count > 0)
{
noncoreImplicants = noncoreImplicants
.OrderBy(i => notCoveredConstituents.Where(c => i.IsSubsetOf(c)).Count()).ToList();
Implicant noncoreTopRatedImplicant = noncoreImplicants[noncoreImplicants.Count - 1];
noncoreImplicants.RemoveAt(noncoreImplicants.Count - 1);
bool covers = false;
for (int i = notCoveredConstituents.Count - 1; i >= 0; i--)
{
if (noncoreTopRatedImplicant.IsSubsetOf(notCoveredConstituents[i]))
{
notCoveredConstituents.RemoveAt(i);
covers = true;
}
}
if (covers)
{
resultImplicants.Add(noncoreTopRatedImplicant);
}
}
return(resultImplicants);
}
/// <param name="implicants">Implicants ordered from short to long.</param>
private static List <Implicant> AbsorpImplicantsToShortDisjunctionNormalForm(List <Implicant> implicants)
{
List <Implicant> resultList = implicants.ToList();
for (int absorperIndex = 0; absorperIndex < resultList.Count - 1; absorperIndex++)
{
Implicant absorper = resultList[absorperIndex];
for (int absorpedIndex = resultList.Count - 1; absorpedIndex > absorperIndex; absorpedIndex--)
{
Implicant absorped = resultList[absorpedIndex];
if (absorper.IsSubsetOf(absorped))
{
resultList.RemoveAt(absorpedIndex);
}
}
}
return(resultList);
}
