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Mar
17
comment Normalisation of an invariant measure
Ilya's example was $P$ is the identity matrix. Then every measure is an invariant measure; and so you can take one then somehow do a weird normalization. The "right question" is to ask for an irreducible Markov chain with this property. Then the answer is no. The issue is that infinite invariant measures arise for null recurrent Markov chains; whereas finite invariant merasure arise for positive recurrent Markov chains.
Mar
8
comment An elementary conditional probability question
The formula appears to describe the following thing: you have a bunch of tests: $1$ to $N$ which accept or reject emails as spam or not; it appears to be assumed that the outcomes of all of these tests are independent. If some tests are passed and some are failed, you are in an indeterminate case. The formula appears to compute the probability of passing all the tests given that you are in the determinate case. Whether this is meaningful, I leave to the computer science types to explain.
Feb
2
comment Total measure and Riesz theorem
Is this a homework question?
Jan
20
comment Cardinality of collection of subfields of $\mathbb C$
Thank you. I guess this is obvious if you know about transcendence bases.
Jan
20
accepted Cardinality of collection of subfields of $\mathbb C$
Jan
20
comment Cardinality of collection of subfields of $\mathbb C$
Thanks - I'm surprised google didn't pull up your question. I did look first.
Jan
20
asked Cardinality of collection of subfields of $\mathbb C$
Jan
18
accepted roots of multi-variable polynomials and extension fields
Jan
9
awarded  Curious
Jan
8
comment roots of multi-variable polynomials and extension fields
I'm reminded of a comment by Miles Reid, who said (I think) that the level of questions that AG people are asked by non-AG people is analogous to the level questions asked by non-mathematicians of mathematicians.
Jan
8
comment roots of multi-variable polynomials and extension fields
Thanks again! I really had in mind $K=\mathbb Q$, but this struck me as a fairly obvious question (it arose from a discussion with a colleague about an integration formula due to Gauss), and I was embarrassed to have no idea about the answer.
Jan
8
awarded  Yearling
Jan
8
comment roots of multi-variable polynomials and extension fields
can i ask 1 more question: is this the lowest tech answer that's possible?(there are quite a lot of words in it that I have heard before, but have no idea what they mean).
Jan
8
comment roots of multi-variable polynomials and extension fields
Thanks Qiaochu.
Jan
8
asked roots of multi-variable polynomials and extension fields
Aug
19
comment Orbit closures of symmetric bilinear form
en.wikipedia.org/wiki/Symmetric_bilinear_form
Jun
16
comment How often does a one-dimensional lazy random walk end at the origin?
This doesn't really seem like a suitable question here to me.
Apr
17
comment Integer solution to the equation
Ummm.. (1) this is not linear algebra; and (2) where does this problem come from?
Jan
28
accepted Measurability Question?
Jan
28
comment Measurability Question?
@PaulMcKenney: In that case it is direct. I just didn't know the definition. Thanks!