public boolean setTeacher (Teacher teach, Field f)	{
	
		//System.out.println("Group.setTeacher() : " + this + " " + teach + " " + f);
		
		if (teach != null && f != null && (this.links.getLinks(f).size() == 0) && teach.canTeach(f, this))	{
			Link l = new Link(teach, this, f);
			teach.addLink(l);
			this.links.add(l);
			return true;
		}
		
		System.out.println("Group.setTeacher() : " + this + " " + teach + " " + f + " " + this.links.getLinks(f) + " " + teach.canTeach(f, this));
		
		return false;
	}