Saharon Shelah

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**Saharon Shelah**
Professor Saharon Shelah in his office in Rutgers University, September 6, 2005. Photo by Andrzej Rosłanowski.
Born	July 3, 1945 Jerusalem, Israel
Residence	Jerusalem, Israel
Citizenship	Israeli
Nationality	Israel
Ethnicity	Jewish
Field	Mathematician
Institution	Hebrew University, Rutgers University
Alma mater	Hebrew University
Academic advisor	Michael O. Rabin
Notable students	Rami Grossberg, Shai Ben-David, Menachem Kojman
Known for	Mathematical logic, Model theory , Set theory
Notable prizes	Wolf Prize, Israel prize
Son of Yonatan Ratosh

Saharon Shelah (שהרן שלח‎, born July 3, 1945 in Jerusalem) is an Israeli mathematician. He is a professor of mathematics at the Hebrew University of Jerusalem and also at Rutgers University in New Jersey, USA. Shelah's main interest lies in mathematical logic, in particular in model theory and set theory.

Shelah is one of the most prolific contemporary mathematicians. As of 2006, he had (together with over 200 coauthors) published nearly 900 mathematical papers. Among his most important results are:

in model theory, the introduction and development of his classification theory, which led him to a solution of Morley's problem
in set theory,
- the invention of the notion of proper forcing, an important tool in iterated forcing arguments
- PCF theory, which shows that in spite of the undecidability of the most basic questions of cardinal arithmetic (such as the continuum hypothesis), there are highly nontrivial ZFC theorems about cardinal exponentiation, after all.

Shelah also solved several outstanding questions from other fields, among them:

He constructed a Kurosh monster, an uncountable group for which every proper subgroup is countable.
He showed that Whitehead's problem is independent of ZFC.
He gave the first primitive recursive upper bound to van der Waerden's numbers V(C,N).
He extended Arrow's impossibility theorem on voting systems.

Shelah is the son of the Israeli poet and political activist Yonatan Ratosh.^[1] His is married to Yael,^[1] and has three children.^[2]

[edit] References

^ ^a ^b Shelah, Saharon (April 5, 2001). זיכרונותיו של בן‎ (Memoirs of a Son) ((Hebrew)). Haaretz. Retrieved on March 14, 2007. “כשעמדתי להציג לפני חברתי יעל (עתה רעייתי) את בני משפחתי…הפרופ' שהרן שלח מן האוניברסיטה העברית בירושלים, בנו של יונתן רטוש…‎”
^ Réka, Szász (March 2001). Harc a matematikával és a titkárnőkkel ((Hungarian)). Magyar Tudományos. Retrieved on March 16, 2007. “Hungarian: A gyerekei mivel foglalkoznak? A nagyobbik fiam zeneelméletet tanul, a lányom történelmet, a kisebbik fiam pedig biológiát. What are your children doing? My oldest son is learning the theory of music, my daughter history, my youngest son biology.”