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visits member for 3 years, 9 months
seen 11 hours ago

Feb
22
asked First-order derivatives in differential forms calculus
Feb
8
asked Solve commutator relation $[Q,d]=-[P,d]$ for $Q$ on chain complexes with scalar product
Jan
8
comment Alternating forms tangential to a subspace.
Corrected. Yes, thanks.
Jan
8
revised Alternating forms tangential to a subspace.
deleted 4 characters in body
Jan
8
asked Alternating forms tangential to a subspace.
Jan
6
comment Nonexistence of a certain norm on $C[0,1]$
Errr... why does $\|\cdot\|_\ast = \|\cdot\|_C$ not fulfill the assumption?
Dec
11
comment Tempered Distribution Calculation
Is there some Stieltjes-integral involved?
Dec
11
comment Stable and efficient projection onto subspace along another subspace
Actually, if I don't err, you do not even need to use Gram-Schmidth for $W$, as the new scalar product as constructed in the original post has been constructed to serve that way. Of course, we can normalize $w_i$ in advance with respect to that product, but that does not improve that substantially. (I think)
Dec
11
asked Stable and efficient projection onto subspace along another subspace
Dec
4
comment How can I compare unbounded linear operators?
Any bounded operator is called unbounded, too, which is completely common, isn't it?
Dec
3
asked How can I compare unbounded linear operators?
Dec
1
answered Projection operator and closed subspaces
Nov
30
revised Well-posedness of the Poisson problem with mixed boundary conditions
additional reference and motivation
Nov
27
comment Can you deduce Neumann boundary data from Dirichlet boundary data?
which, btw, tells about us that we cannot impose Neumann and Dirichlet boundary conditions simultaniously.
Nov
26
asked Well-posedness of the Poisson problem with mixed boundary conditions
Nov
16
awarded  Yearling
Nov
11
comment Can metric properties can be expressed in category theoretical terms?
@Rasmus: We indeed have this equivalence. But besides the algebraic statement, that the dualization functor is naturally equivalent to an endofunctor, I also would like to express in categorial terms that this equivalence holds. In contrast, the norm of the dual morphism could have no relation at all to the original morphism. Such a functor would be useless for analytic purposes.
Nov
11
asked Can metric properties can be expressed in category theoretical terms?
Nov
9
asked How strong does a matrix distort angles? How strong does it distort lengths anisotrolicly?
Oct
23
comment Are integrations on forms “different” from Riemann integrations?
Could you explain, why the Riemann integral is prefered over the Lebesgue integral in this case - or rather, why it is enforced by the structure of the theory?