Plouj

                public boolean equals(Object obj) {
                        boolean equal = false;
                        if(this == obj)
                                return true;
                        if((obj == null) || (obj.getClass() != this.getClass()))
                                return false;
                        // object must be FunctionalDependency at this point
                        FunctionalDependency FD = (FunctionalDependency)obj;
                        if ( LeftHandSide.size() == FD.LeftHandSide.size() &&
                                        RightHandSide.size() == FD.RightHandSide.size()) {
                                for (String s : LeftHandSide) {
                                        if (!FD.LeftHandSide.contains(s)) {
                                                return false;
                                        }
                                }
                                for (String s : RightHandSide) {
                                        if (!FD.RightHandSide.contains(s)) {
                                                return false;
                                        }       
                                }       
                                return true;
                        } else {
                                return false;
                        }
                }


...
                        Rinitial = new Relation();
                        FunctionalDependency fd = new FunctionalDependency();
                        String s;
                        s = "A"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "B"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed1"); }
                        s = "B"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed2"); }
                        s = "C"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "D"; if (!fd.addRHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "E"; if (!fd.addRHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "F"; if (!fd.addRHS(s)) { System.out.println("add "+s+" failed"); }

                        if (!Rinitial.add(fd)) {System.out.println("adding "+fd+" failed1");}
                        if (!Rinitial.add(fd)) {System.out.println("adding "+fd+" failed2");}

                        fd = new FunctionalDependency();
                        s = "A"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "B"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "C"; if (!fd.addLHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "D"; if (!fd.addRHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "E"; if (!fd.addRHS(s)) { System.out.println("add "+s+" failed"); }
                        s = "F"; if (!fd.addRHS(s)) { System.out.println("add "+s+" failed"); }

                        if (!Rinitial.add(fd)) {System.out.println("adding "+fd+" failed3");}

                        System.out.println(Rinitial);

... prints:
adding 'A', 'C', 'B' -> 'D', 'F', 'E' failed2
['A', 'C', 'B' -> 'D', 'F', 'E'] ['A', 'C', 'B' -> 'D', 'F', 'E']