Speaker: Yaaqov Loewinger (Tel-Aviv)                                            
                                                                                
Title: "Which Tequfa is relevant for intercalation and how it works? New        
        aspects (I)"                                                           

Abstract 
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Which Tequfa was meant in the Talmudic sugyot (sheela in prayer, fixing
cardinal directions, birkat ha-hamma, heathen feasts, solar season-related
acts, intercalation), where the notion of Tequfa was mentioned? 

Which Tequfa was meant in the Talmudic sugyot dealing with intercalation
in Bavli, Sanhedrin 11a-13b, and Rosh Hashana 21a? 

According to early Ashkenazi Rishonim (Rashi, Tosafists till ~ 1200 CE):
only Tequfat Shemuel was considered, but according to early Sefaradi
calendar experts (Hassan ha-dayyan, Hanassi, Yehuda ha-Levi, Ibn Ezra,
ReMa"H Abulafiyya, Rambam, Yisraeli etc.) only Tequfat R. Adda was
considered for intercalation. What was said by modern scholars (Slonimsky,
Pineles, Bornstein, Sar-Shalom etc.) on that? 

The notions of astronomical mean and true (= apparent) equinox. Which one
is relevant for intercalation? 

I argued in my book Al ha-Sheminit (Tel-Aviv, 1986) that only the true
Nisan equinox is relevant for intercalation and Tequfat Nisan of R. Adda
represents this true equinox in our calendar. 

This stand was seriously attacked in a recent article with very weighty
arguments by Eng. J. J. Ajdler from Belgium, and was questioned by other
experts too. Rambam's opinion. 

Where do we stand now?