Today's daf is sponsored by Suri Stern in honor of her son's, Yosef Yeshaya's, marriage yesterday to Rivkah Cohen. "May they be zocheh to build a bayit neeman b’yisrael, a binyan adei ad." Beit Shamai and Beit Hillel disagree regarding mi'un (refusal) on five different issues: Can a girl only do mi'un only from engagement or also from marriage? Can she "refuse" the yabam also if her husband dies? Does it need to be done in her husband's presence? It is necessary to do it in a court? Can she do it to several different husbands or only one? Four different explanations are brought to explain why Beit Shamai holds that one cannot do mi'un after marriage. Is it due to concern that one may think one can do a marriage upon condition? Or because one does not want to engage in intercourse when in the end it will turn out to be znut, as they will retroactively not be married if she refuses him. Or because if he knows she may refuse him, he may use up even part of the principle of her assets she brings into the marriage. Or because he will not want to marry her out of concern that all the expenses on the wedding feast will go to waste if she later refuses. According to Beit Hillel, she can also do mi'un to the yabam. Rabbi Oshaya and Ulla disagree about whether her mi'un to a yabam can undo the zika or can only undo ma'amar. The reasoning behind each approach is explained and a difficulty is raised against each but is resolved. There is a three-way debate regarding the ramifications of refusing her yabam - is she forbidden now to do yibum with him, forbidden also to all the brothers, or permitted even to him? What is the reason behind each approach? Beit Hillel brings an actual case of Pishon the camel driver, who was refused not in his presence in order to disprove Beit Shamai's opinion. But they explain that he dealt with her inappropriately and therefore the rabbis were permitted to deal with him inappropriately and permit refusal even not in his presence. Regarding the debate about whether or not a court is required, what exactly are the different opinions? There is a debate regarding how to understand the last line in the Mishna regarding Beit Shamai's opinion about whether she refuses once, when can she remarry and what does she need to do before she remarries.