2,648 reputation
2033
bio website ephorie.de
location Germany
age 44
visits member for 4 years, 3 months
seen Oct 14 at 20:03

just an amateur fascinated by math


May
12
comment Difference between metric and norm made concrete: The case of Euclid
I think I finally got it - Thank you to everybody!
May
12
comment Connections between metrics, norms and scalar products (for understanding e.g. Banach and Hilbert spaces)
@Theo: You are right! Thank you very much for that hint! I switch constantly between both languages. I found that oftentimes the part that is missing for a proper understanding in one language is to to be found in the other. There are so many texts in German that are not translated and of course the other way round. BTW: The site of Dirk Werner is to be found here: page.mi.fu-berlin.de/werner99 - there are some free texts, e.g. this one about Fixpunktsätze that seems to be very understandable too: page.mi.fu-berlin.de/werner99/skripte/fixpunkte.pdf
May
12
comment Difference between metric and norm made concrete: The case of Euclid
@Qiaochu: Thank you. Perhaps my confusion stems from the fact that on the one hand, as you say, you can do it either way, on the other hand there is this hierarchy between metric spaces and normed spaces (every normed space is a metric space but not the other way round). It seems like a contradiction to me...?!?
May
12
comment Difference between metric and norm made concrete: The case of Euclid
@user6312: Thank you - could you please give an example of a simple metric that is not translation invariant?
May
12
asked Difference between metric and norm made concrete: The case of Euclid
May
12
accepted Connections between metrics, norms and scalar products (for understanding e.g. Banach and Hilbert spaces)
May
11
comment Connections between metrics, norms and scalar products (for understanding e.g. Banach and Hilbert spaces)
@Theo: This one is interesting: Could you give an intuitive example of a metric where you don't have a norm? Perhaps I am not thinking abstractly enough but if you can define the distance of a vector from the origin you must also be able to measure the length between two points defined by vectors, or not?!?
May
11
asked Connections between metrics, norms and scalar products (for understanding e.g. Banach and Hilbert spaces)
Apr
17
accepted Why is the ratio test for L=1 inconclusive?
Apr
17
asked Why is the ratio test for L=1 inconclusive?
Apr
11
accepted How to solve combinations of differentials and integrals?
Apr
11
comment How to solve combinations of differentials and integrals?
Thank you - esp. the section "variable limits" is relevant.
Apr
11
comment How to solve combinations of differentials and integrals?
Thank you! Why do you have an extra term in (b) and two extra terms in (c)? Because you have to differentiate acc. to the boundaries of the integral? But in (a) you also have boundaries (- to + infinity)???
Apr
11
asked How to solve combinations of differentials and integrals?
Apr
5
accepted Connection between chain rule, u-substitution and Riemann-Stieltjes integral
Apr
5
comment Connection between chain rule, u-substitution and Riemann-Stieltjes integral
Thank you for this very enlightening answer!
Apr
5
comment Connection between chain rule, u-substitution and Riemann-Stieltjes integral
@lhf: Thank you, I found that already - I think it gives only part of the answer and not the big picture.
Apr
5
asked Connection between chain rule, u-substitution and Riemann-Stieltjes integral
Apr
5
answered Function example? Continuous everywhere, differentiable nowhere
Mar
30
awarded  Taxonomist