public Teacher getTeacher(Field f)	{
		//System.out.println("Group.getTeacher(" + f + ") " + this + " " + this.links.size() + " " + this.links.getLinks(f));
		return (this.links.getLinks(f).size() != 0 ? this.links.getLinks(f).get(0).getTeacher() : null);
	}