User maximiliano valle - MathOverflow most recent 30 from http://mathoverflow.net 2013-05-25T10:31:53Z http://mathoverflow.net/feeds/user/7837 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/36348/infinitely-many-linear-equations-in-infinitely-many-variables/42980#42980 Answer by Maximiliano Valle for infinitely many linear equations in infinitely many variables Maximiliano Valle 2010-10-21T01:39:17Z 2010-10-21T01:39:17Z <p>I would recommend taking a look at Hardy's "Divergent Series" it has quite a lot of nice ideas, in particular, I recall seeing exactly that example of a system of infinite equations in infinite unknowns related to fourier series.</p> http://mathoverflow.net/questions/42410/what-is-the-dual-concept-to-annihilator-called-and-do-any-linear-algebra-textb/42417#42417 Answer by Maximiliano Valle for What is the dual concept to "annihilator" called, and do any linear algebra textbooks discuss this concept first? Maximiliano Valle 2010-10-16T21:12:15Z 2010-10-16T21:27:21Z <p>In the book "Algebra Lineal y Geometría" by Angel Rafael Larotonda, he introduces the concept right after introducing the annihilator of a set $M\in V$ as $M^o$, he introduces the "left" annihilator of a set $F \in V^*$ as $^oF=${$x \in V: f(x)=0 \; \forall \; f \in F$}, the only problem is that its written in spanish. I have also seen the concept introduced directly as pre-annihilator, but alas, also in spanish books.</p> http://mathoverflow.net/questions/129949/when-does-second-annihilator-of-a-principal-ideal-equal-the-ideal-itself-ie Comment by Maximiliano Valle Maximiliano Valle 2013-05-07T12:00:32Z 2013-05-07T12:00:32Z Quasi-Frobenius Rings are precisely the (Artinian) rings that Ann(ann(I))=I, ann(Ann(T))=T , Ann= right annihilator, ann=left annihilator. http://mathoverflow.net/questions/52312/complex-function-rouches-theorom Comment by Maximiliano Valle Maximiliano Valle 2011-01-17T13:40:19Z 2011-01-17T13:40:19Z <a href="http://math.stackexchange.com/" rel="nofollow">math.stackexchange.com</a> http://mathoverflow.net/questions/43346/combinatorial-equation Comment by Maximiliano Valle Maximiliano Valle 2010-10-24T02:25:36Z 2010-10-24T02:25:36Z @Will: You get $4=4$ if you accept that $0^0=1$ http://mathoverflow.net/questions/42410/what-is-the-dual-concept-to-annihilator-called-and-do-any-linear-algebra-textb/42417#42417 Comment by Maximiliano Valle Maximiliano Valle 2010-10-17T00:38:26Z 2010-10-17T00:38:26Z In my opinion, it isn't that &quot;all our linear algebra books are this bad&quot;. It's the mathematic trend to teach the concept from which you can branch a lot of stuff than the motivation, concrete examples. I think this <a href="http://mathoverflow.net/questions/19152/why-is-a-topology-made-up-of-open-sets" rel="nofollow" title="why is a topology made up of open sets">mathoverflow.net/questions/19152/&hellip;</a> question in MO can explain very clearly what I have in mind.