If you are certain that he is coming prepared for murder - אי פשיטא לך דאנפשות קאתי
Summary:
If there is doubt whether the intruder will kill, then באב על הבן, he may not be killed; however by בן על האב (and anyone else) the intruder may be killed.
From when is it forbidden to do work on the fourteenth? - מאימתי י"ד אסור בעשיית מלאכה
Summary:
According to רש"י, the dispute between ראב"י and ר"י is concerning a place where the מנהג is not to do מלאכה on ע"פ. According to תוספות they argue concerning גליל where it is forbidden to do מלאכה on ע"פ.
ראב"י maintains from the time of 'Ohr' -
רבי אליעזר בן יעקב אומר משעת האור
Summary:
ראב"י maintains that the prohibition begins at the beginning of the day which is עלות השחר, while ר"י maintains that the prohibition from work begins when people usually begin to work; נץ החמה.
Where do we find a day where partially it is permitted and partially it is forbidden - היכן מצינו יום שמקצתו מותר ומקצתו אסור
Summary:
A day may be divided into times of היתר ואיסור when there is a logical reason for it; however when there is no logic then (according to ראב"י) there is no day שמקצתו מותר ומקצתו אסור.
