Jewish Calendar Seminar

There are two types of people in the world - those who find the details of the intercalation of the Jewish calendar to be an extremely arcane and dull subject and those who delight in its intricacies. For the latter group, I report the following (note the refreshments):

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Jewish Calendar Seminar
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The first meeting of the seminar this year will take place, IYH,

(when) Wednesday, 19 Marcheshvan (Nov. 3), at 4:00 pm
(preceded by refreshments at 3:45 pm)

(where) Room 331 (Math Dept Seminar Room),
Math and CS Building, Bar-Ilan University

Eng. Yaaqov Loewinger
(Tel-Aviv)

will talk about

"The 8th in the 19-year cycle of the Hebrew calendar:
another look at "Al ha-Sheminit'"


Note: This talk, as most others in this seminar, will be held in Hebrew.
Talks are held once every two weeks.

Abstract:
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On Rosh ha-Shana 5765 we entered the 8th year of the 304th 19-year cycle of the Hebrew calendar. It is well-known that the intercalation of this year (and of some other years as well) poses some serious calendric problems: it seems this intercalation is not necessary in order to achieve the main objective of the Hebrew calendar, namely to cause the relevant days of Pesah 5765 to fall after the Vernal Equinox.

In the year 5746 (1986 CE), the 8th year of the previous cycle, we investigated this problem in a special booklet called "Al ha-Sheminit". We analyzed there also the essence of the intercalation rule of our calendar, established its sources and drew conclusions regarding the possible date of its establishment. We formulated there also the Basic Rule of the Hebrew Calendar and its mathematical build-up. This enabled us to fix some simple mathematical formulae for the necessary calendar calculations, especially fitted for calculator and computer usage.

In our talk we will review the essence of the above booklet, and point to some principles which were severely criticized by some important calendar authorities, and need to be revised or at least re-formulated.