understanding the Concept of מבטל כלי מהיכנו (Nullifying a Vessel from Its Usage);
ודבר דבר (Dabair Davar): Mentioning Something That Somebody Will Do After Shabbos When It's Not Allowed to Be Done on Shabbos Itself;
ודבר דבר (Dabair Davar): Talking About Calculations on Shabbos;