Understanding "פסיק רישא דלא ניחא ליה" (inevitable results from one's permissible action whereby one receives no benefit from).
The Separation Has to Be with אוכל and פסולת (Good and Bad);
Introduction to the Concept of עובדא דחול (Uvda d'Chol) in Relation to the Melacha of M'AMER;