Einstein-Penrose ‘s strong sum convention


the rank one tensors’ basis changes

abstractrelativity017

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a level surface


A level surface f^{-1}(1) for the function f(x,y,z)=x^2+y^2+z^2-3xyz
levelsurf014

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splitting into handlebodies


spleeti

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short exact sequence and center


Let us prove:

Let 1\to A\stackrel{f}\to B\stackrel{g}\to B/A\to 1 be a short exact sequence, if the center Z(B/A)=1  then Z(B)<A

Proof:  When x\in Z(B) then g(x)\in Z(B/A), so g(x)=1.

Therefore x\in\ker (g)={\rm im}(f)=A

\Box

 

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Pascal’s Rule and double induction


If S is a set with \#S=n and T\subset S such that \#T=k then there are {n\choose k} different of them.

Follow the link pascalbernoulli for a double induction proof.

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primer parcial, examen de multi


aplicado ayer √

1erexamAlMu

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three jordan two-by-two matrices and exponential


temareas?

How many three-by-three forms are there?

: )

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