public List<Sentence> plResolve(Sentence clause1, Sentence clause2)
{
List<Sentence> resolvents = new List<Sentence>();
ClauseSymbols cs = new ClauseSymbols(clause1, clause2);
List<Symbol> complementedSymbols = cs.getComplementedSymbols();
foreach(Symbol symbol in complementedSymbols)
{
resolvents.Add(createResolventClause(cs, symbol));
}
return resolvents;
}