Hope you don't mind a question that is a few weeks away from the current Daf but I am learning Hilchos Shabbos Melacha Kosher.
The Mishnah brings Rabbi Elazar bar Yaakov that one may tie a rope in front of an animal so that it shouldn't escape.
The Gemora explains that we might have thought that the person will only untie one side (or one of the ropes) leaving the other one tied which would be a problem of a kesher shel kaimer.
What sort of knot are we talking about is it 1) a double knot or 2) only a single knot with a bow
Michoel Singer, Manchester, M25 0LU
Shalom
It is very important to learn the Mishnah Brurah's introduction to the Malacha of Kosher (OC:317). He quotes two major approaches. According to the Ramabam the Torah prohibition applies only to a knot which is both a professional one (Ma'aseh Uman) and a permanent one. A knot lacking one of these two is Assur Mid'Rabanan. A knot with neither of these qualifications is permissible.
Rashi, on the other hand, maintains that the quality of the knot does not play any role here. The Torah prohibition applies to a permanent knot. A knot meant to last for a while but not forever is Asur Mid'Rabanan. A knot which will be undone in the very near future is permissible.
This should answer your query. According to the Rambam we are permitting a non-professional knot only, while according to Rashi any type of knot is permissible under the circumstances.
Yehuda Landy