Monthly Archives: October 2006

Cardinal Arithmetic

I just came across Saharon Shelah’s website. I had heard of him in the context of the Whitehead problem before (is every abelian group $A$ such that $Ext^1(A,\mathbb{Z})=0$ free?). Shelah proved, amazingly (at least to me), that the Whitehead problem … Continue reading

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Why I’m not a topologist

Yes, I’m still alive. This quarter my favorite class is on knot theory. In particular, we are studying Khovanov homology. The point of Khovanov homology is to give a stronger knot invariant than the Jones polynomial which also has nice … Continue reading

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