bio | website | regularize.wordpress.com |
---|---|---|

location | Braunschweig, Germany | |

age | 36 | |

visits | member for | 4 years, 7 months |

seen | 5 hours ago | |

stats | profile views | 1,941 |

Professor at TU Braunschweig.

Area: Inverse problems, regularization theory, applied functional analysis, mathematical image processing.

May 20 |
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Projecting a convex partition onto a convex set
Err, sorry - of course, nonempty $X$ it should be… |

May 20 |
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Projecting a convex partition onto a convex set
$X$ could be empty or have $n-1$ points... You need some more conditions. |

May 19 |
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Splines linearly independent
What do you mean by "its unique smooth extension"? |

May 14 |
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Which way for reading the proofs?
@fanzheng I heard a similar quote about a famous optimizer "I don't read papers, I write them." |

Apr 23 |
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l1 Quadratic Programming
Noting that the above problem has all these guys as variables: Isn't that in standard for already? |

Apr 23 |
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A question involving Mazur's Lemma
Well, the degenerate case $y_n = x_n$ does not work so some assumption on the convex combination is needed. |

Apr 14 |
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2, 3, and 4 (a possible fixed point result ?)
As far as I understood, the BGK (Browder-Göhde/Göbel-Kirk) fixed point theorem states that every non-expansive self-mapping on a non-empty, closed and convex subset of a uniformly convex Banach space has a fixed point. |

Mar 27 |
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Hadamard / matrix product adjoint
Ok, I see now. I think a better fit for this question would be scicomp.stackexchange.com. Anyway: The adjoint is defined by $\langle A^* y,x\rangle = \langle y,Ax\rangle$. You do adjoints one by one from outside to inside. |

Mar 26 |
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Hadamard / matrix product adjoint
Sorry, but this does not make sense. What is the Hadamard product of the matrix S and the vector Fx? |

Mar 26 |
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Hadamard / matrix product adjoint
Err... So x is a matrix? |

Mar 26 |
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Hadamard / matrix product adjoint
I could not parse your definition of the operator A. If D and S are matrices, do you build the Hadamard product with the matrix of the Fourier transform? |

Mar 26 |
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Convergence in energy of bounded (semi)subharmonic functions
Sorry for the late reply: I guess the best thing would be to write an answer yourself so that this is kept for the records. |

Mar 17 |
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Fredholm integral with functions constrained to [0;1]
For some reason I confused $g$ and $f$. Of course $f$ should be the unknown… Corrected. |

Mar 16 |
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Fredholm integral with functions constrained to [0;1]
The most simple thing that comes to mind is the projected gradient method, see my update. |

Feb 27 |
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What is an extragradient method?
Well, this shows that the term "extragradient" is indeed used differently. |

Feb 19 |
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Different styles of writing/reading articles
@FedericoPoloni I agree. When I wrote the comment, this question was closed without an answer, so it was unclear if it would ever get any answers here… |

Feb 19 |
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Different styles of writing/reading articles
Probably this question will get answers over at academia.stackexchange.com |

Feb 17 |
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How to solve the following generalized quadratic programming problem
Well its still convex, albeit non-smooth. Looks like primal-dual methods, alternating direction method of multipliers or so could be applied… |

Feb 2 |
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optimization of inverse matrix with constraint on matrix elements
Have you tried to formulate the optimality system, e.g. by using this: en.wikipedia.org/wiki/… |

Jan 27 |
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Reference : Special case of Banach-valued function integration by parts
I would start looking in Zeidler's books on functional analysis but I don't have access right now. |