# Martin

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 Apr22 awarded Nice Question Apr7 comment Antisymmetric functions in higher dimensions Okay, maybe a nice definition of signed permuation of coordinates is a permuation matrix times a ${-1,1}$-diagonal matrix, and the signum is the determinant of that transform. Apr7 comment Antisymmetric functions in higher dimensions That's interesting. Your functions are smooth, are they? And could you please define what a signed permuation and its signum mean? Apr2 asked Cyclic containment of sets Mar18 comment How should I understand “$A$ unless $B$”? That post is nicely written. Thanks! Mar13 comment Derivative in complex analysis @anon: I am curious and my complex analysis is rusty, too. Why is $f$ constant? Mar13 answered I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent Mar7 awarded Tumbleweed Mar7 comment Which formula do I use to integrate $\int {\sqrt{x^2 + 81} \over 2} \,dx$ In your final expression, the variable $x$ appears outside the integral, without any proper definition there. You should change this notation. Mar1 comment First-order derivatives in differential forms calculus Because that is the way the Lie differential is defined. Feb26 awarded Taxonomist Feb22 comment What is the theory of non-linear forms (as contrasted to the theory of differential forms)? I guess these non-linear forms are taken from David Bachmann's book "A Geometric Approach to Differential Forms", aren't they? Feb22 revised First-order derivatives in differential forms calculus added 75 characters in body Feb22 asked First-order derivatives in differential forms calculus Feb8 asked Solve commutator relation $[Q,d]=-[P,d]$ for $Q$ on chain complexes with scalar product Jan8 comment Alternating forms tangential to a subspace. Corrected. Yes, thanks. Jan8 revised Alternating forms tangential to a subspace. deleted 4 characters in body Jan8 asked Alternating forms tangential to a subspace. Jan6 comment Nonexistence of a certain norm on $C[0,1]$ Errr... why does $\|\cdot\|_\ast = \|\cdot\|_C$ not fulfill the assumption? Dec11 comment Tempered Distribution Calculation Is there some Stieltjes-integral involved?