# Saharon Shelah: Hilbert's First Problem and the number four

Saharon Shelah, Hebrew University of Jerusalem, Israel

**Time: **Wed 2009-09-23 16.00 - 17.00

**Location: **Room 3721, department of mathematics, KTH, Lindstedtsvägen 25, 7th floor

Hilbert's First Problem was about the continuum hypothesis, so really about: is the arithmetic of infinite numbers simple? What are its rules? The talk will be exclusively in naive set theory, and does not assume any specialized knowledge. We try to exemplify the idea, that when we ask the right question there is much to be said, even restricting ourselves to sets of reals only.