Questions tagged [nonlinear-optimization]
Nonlinear objectives, nonlinear constraints, non-convex objective, non-convex feasible region.
656 questions
0
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Numerically finding constrained critical points
Suppose $m, n, p, n_c\in\mathbb{N}$, $Y\in\mathbb{R}^{m\times p}$. Let $\mathcal{P}_{m, n, p} := \mathbb{R}^{m\times n}\times\mathbb{R}^{n\times p}\times\mathbb{R}^{m\times p}$ and $g:\mathcal{P}_{m, ...
1
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0
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122
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On the largest Eigenvalue of a certain "graph Laplacian"
I am interested in the following problem, which came up while working on this paper about estimating Betti numbers of Kähler manifolds, where we were not able to solve it and had to resort to ...
0
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0
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68
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Escape from saddle points?
My question is related to a very concrete minimization problem that cannot be treated by https://proceedings.mlr.press/v70/jin17a/jin17a.pdf
Denote $\Omega:=\mathbb R^d$ with $d\in \{2,3\}$. We adopt ...
1
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0
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58
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Comparision theorem for nonlinear integral Volterra equations with parameters
I am looking for comparision results for nonlinear integral Volterra equations with parameters. This was partially motivated by this paper. There, the author establishes, under mild hypothesis, the ...
1
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0
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37
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Numerical method to search local minimizers for non convex functions
Let $f:\Omega \to\mathbb R$ be semi-concave and Lipschitz, where $\Omega\subset\mathbb R^d$ is convex and closed. Consider the minimization problem (assuming the existence of a minimizer)
$$\inf_{x\in ...
1
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0
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141
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Solving equations on a high dimensional torus
I want to establish some useful criteria for uniqueness of solutions to the following:
$$Mx=b,\\ \text{subject to}\ ||x(2k-1:2k)||=1, k=1,2,\cdots,5,$$ where $M\in\mathbb{R}^{10\times10},\ x\in\mathbb{...
2
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0
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117
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Optimization problem for threshold functions
Let $S_m=\{-1,1\}^m$ be the hypercube of signs. Define the set of "admissible weights" $W_m$ as the subset of $\{w\in\mathbb{R}_+^m : \|w\|^2=m\}$ with a "support property" of the ...
7
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1
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815
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Softest transition from 0 to 1 on the real axis in minimum time
We want to get from 0 to 1 on the real axis with a moving point $P(x(t))$, that moves only in the right direction, as soft as possible in a minimum time. We introduce the class $\mathcal{S}$ ...
1
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0
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268
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Question related to Feige conjecture
I am sorry if the question is quite strange, but I will try. Suppose $X_1$,...,$X_N$ are independent non-negative random variables having values in $[0,N+1]$. The expectation of all of them is $\...
3
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1
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166
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Exchanging norms of proximal operators
I have two friendly functions $g,h:\mathcal{X}\subseteq\mathbb{R}^N\to\mathbb{R}$ whose exact properties I'm somewhat flexible on. Maybe for starters they are lower semi-continuous and convex. Their ...
7
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223
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Define a finite subgroup of a Lie group by minimising a function
The Thomson problem on the $S^2$ sphere asks what configuration(s) of $N$ points minimize a particular function which is symmetric under all permutations of its arguments,
$$F(x_1,\ldots,x_N) = \sum_{...
0
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0
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40
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How to robustly optimize a point based on gradient alignment with multiple implicit ellipses?
I'm trying to optimize a 2D point $p = (x_p, y_p)$ given a set of 2D points $q_i \in \mathbb{R}^2$ and associated direction vectors $G_i \in \mathbb{R}^2$.
Each point $q_i$ is assumed to lie on an ...
0
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1
answer
209
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How to design encoders with the minimum number of rows?
Assume that matrices $\mathbf{A}$, $\mathbf{B}$, and $\mathbf{C}=\mathbf{A}\mathbf{B}$ are given. I aim to find matrices $\mathbf{E}_1$, $\mathbf{E}_2$, and $\mathbf{E}_3$ such that
\begin{align}
\...
2
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0
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162
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On the expected quality of a rank-$1$ approximation of a complex Gaussian noise covariance matrix
I am developing quality coefficients for a specific type of approximation of covariance matrices. I want to to specify meaningful lower bounds (or rather thresholds), for which I would like to use the ...
2
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0
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96
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Designing a loss function in the form of a linear combination
I have functions $f : \Bbb{R}^n \to \Bbb{R}_{\geq 0}$ and $g : \Bbb{R}^n \to \Bbb{R}_{\leq 0}$ and would like to find a $\mathbf{x}_* \in \Bbb{R}^n$ where $g(\mathbf{x}_*)=0$ and $f \left( {\bf x}_* \...
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69
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Is the norm of the gradient of the Moreau-envelope non-decreasing in $\lambda$?
Let $f$ be an $\rho$-weakly convex function, $f:\mathbb{R}^d\to \mathbb{R}$. The Moreau envelope of $f$, $f_\lambda$ for a parameter $0<\lambda<1/\rho$ is defined as
$$ f_{\lambda}(x) := \min_{y}...
0
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0
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59
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Determining the general terms of two increasing sequences in order to generate an equally spaced composite sequence via arctangent mapping
Consider two strictly increasing positive sequences $a = \{a_i\}_{i=1}^m$ and $b = \{b_j\}_{j=1}^n$, where the maximum terms satisfy $a_m = M > 0$ and $b_n = N > 0$. Define a composite sequence $...
0
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0
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39
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Does a $C^1$ diffeomorphism of open sets up to the boundary preserve feasible direction cones, especially when the open sets arise as epigraphs?
Let $U \subset \mathbb{R}^n$ be an open set. Let $\Phi : \bar{U} \to \bar{\Phi(U)}$ be a $C^1$ diffeomorphism defined up to the boundary (i.e., $\Phi$ is a diffeomorphism from an open set containing $\...
1
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1
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183
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Is the tangent cone to the epigraph of a Lipschitz function with existing directional derivatives the epigraph of its directional derivative function?
Let $f : \mathbb{R}^n \to \mathbb{R}$ be a locally Lipschitz function, and let $\bar{x} \in \mathbb{R}^n$. Assume the directional derivative
$$
f'(\bar{x}; v) := \lim_{t \downarrow 0} \frac{f(\bar{x} +...
1
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0
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53
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Extension of the Ioffe-Tikhomirov theorem to locally Lipschitz functions with the Clarke subdifferential?
More precisely, assume that
$f:X\times Y\to
\mathbb{R} \cup \{+\infty \}$ is a function where $Y\subset X$ is compact,
$\partial_{x}^{C}f\left( x_{0},y\right) $ is the Clarke
subdifferential of at $...
5
votes
1
answer
481
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Is there an efficient method to solve this optimization problem on the surface of the sphere?
Let $A$ be a non-singular matrix in $\mathbb{R}^{n \times n}$. Let $S^{n-1}$ denote the surface of the unit $n$-sphere in $\mathbb{R}^{n}$. Suppose we know that there exists an $x \in S^{n-1}$ such ...
3
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0
answers
110
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Which function does this cross section optimize?
I often notice tankers of the type illustrated in the figure below.
The cross section is neither circular nor elliptical. Is it a "notable" geometric shape?
Which function or property does ...
0
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0
answers
78
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Choice of terminology (Critical Points v.s Stationary Points or etc.) in the calculus of variations
Thanks for experts on the terminology-related questions.
Given a Banach space $X$ and an open subset $U\subset X$, a functional $\mathscr{F}:U\mapsto \mathbb{R}$. What is the standard terminology of ...
0
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0
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75
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Why doesn't Lagrangian multiplier give any useful message for matrix optimization problem?
Let $\mathcal{H}^n$ be the space of dimension-$n$ Hermitian matrix space. Given $A\in\mathcal{H}^n$, consider the following optimization problem:
\begin{align*}
&\max f(X,Y)=\text{tr}(XAYA)-\...
2
votes
0
answers
39
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Reference for the solution of this optimization problem that shows up in linear discriminant analysis
I'm looking for a reference to the solution of trace-ratio linear discriminant analysis with an orthogonality constraint. Consider the following optimization problem where $A$ and $B$ are symmetric ...
0
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1
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213
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How to calculate the maximum dimensions of a rectangle inside two concentric circles? [closed]
If I have a rectangle ABCD such that A and B touch two points of the outer circle and CD's touches one point of the inner circle, how could the maximum dimensions of the rectangle be calculated?
...
1
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0
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123
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Markov Chain that maximises the entropy creation rate
I am working on MERW (Maximal entropy random walk) for a project.
I want to show that given a graph G, there is $\textbf{only one}$ aperiodic markov chain on G that maximises the entropy creation rate ...
1
vote
0
answers
58
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Change in active constraints when perturbing the objective of a QP
Suppose I have a quadratic program (with positive semidefinite cost matrix) with affine (polytopic) constraints. It is known that the solution to this is piecewise affine, with the ``pieces'' defined ...
3
votes
0
answers
199
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An optimisation problem
Let $E\subset \mathbb R^2$ be compact, convex and connected. For $p_1,\ldots, p_n>0$ with
$$\sum_{i=1}^n p_i=1,$$
and a probability measure $\nu$ supported on $E$ of density $f$, we consider
$$\...
0
votes
1
answer
128
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Optimizing sum of discrete minimum
Please consider the following optimization problem: Given a fixed positive natural $n < N$, and a set of functions $f_i$ over a finite domain of nonnegative outputs, s.t. $1 \le i \le N$, then we ...
1
vote
0
answers
46
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Critical point of perturbed stratifiable function has no cluster point
Given a smooth function $f:\mathbb{R}^d\rightarrow\mathbb{R}$ and a smooth manifold $\mathcal{M}$. Now, consider the set
$$
S(v)=\{x:0\in x\circ(\nabla_{\mathcal{M}} f(x)+N_{\mathcal{M}}(x)+v)\}.
$$
...
-2
votes
1
answer
163
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Prove the function $g(x,y,t)\ge1$
I have the function
$$
g(x,y,t)=\frac{(8x^2y^2+f_+(x,y,t)-\cos(2t))(8x^2y^2(1+(x+y)^2)+(x+y)^2(f_-(x,y,t)-\cos(t))+4xy(x+y)\sin(2t))}{64x^4y^4(1+(x+y)^2)}
$$
with
$$
f_{\pm}(x,y,t) = 1+2x^2+2y^2\pm4xy\...
0
votes
1
answer
140
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Transform a matrix optimization problem into a semidefinite programming
I am working on a matrix optimization problem, and the constraints are difficult to handle.
The constraints are in the following form,
\begin{align}
\text{Given: } &b \in \mathbb{R}^n \text{ , and ...
2
votes
1
answer
214
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Why rough path theory principle is not applied in parameter estimation of stochastic differential equation(SDE)?
My apologies if this question is not proper for this site, but I could not figure out the following. Can anyone provide insight? It is almost certain that stochastic differential equations (SDEs) can ...
4
votes
0
answers
270
views
What is the maximum tidal force between two objects with unit volumes and unit density?
Motivation for this problem
This problem arises from the fact that the derivative of the gravitational force (tidal force) in the $z$-direction between two objects $A$ and $B$, which have equal ...
5
votes
0
answers
659
views
What is the correct $L^\infty$ limit of this strange variational problem, and what does it encode?
1. On the $L^\infty$ calculus of variations:
The field known as the $L^\infty$ calculus of variations is a relatively new field that concerns itself with minimising functionals involving the supremum ...
4
votes
1
answer
293
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Does this functional admit an absolute minimizer?
This is a close relative of the following problem.
Let $\Omega$ be an open, bounded subdomain of $\mathbb R^n$ with smooth boundary, and $f_i \in W^{1, \infty} (\Omega)$ a sequence of functions ...
11
votes
2
answers
499
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Maximization of a cubic form over the $14$-dimensional sphere
For any integers $i$ and $j$ such as $1\le i<j\le6$, let $x_{ij}$ be a nonnegative real number.
Is it true that, given the condition
$$\sum_{1\le i<j\le6}x_{ij}^2=1,$$
the sum
$$\sum_{1\le i<...
6
votes
2
answers
558
views
Does this polynomial have a real zero less than or equal to $1/2$?
Is the smallest root $x$ of
$$
10x^{3}-30x^{2}+\left(30-2\sum_{1\le i<j\le6}\cos^{2}\alpha_{ij}\right)x\\
+2\sum_{1\le i<j\le6}\cos^{2}\alpha_{ij}-\sum_{1\le i<j<k\le6}\cos\alpha_{ij}\cos\...
9
votes
3
answers
2k
views
Smallest root of a degree 3 polynomial
Is it true that the smallest root $t$ of the polynomial
$$
20 t^3 - 30 t^2 + (12 - 4 \cos^2 \alpha - 4 \cos^2 \beta - 4 \cos^2 \gamma) t + \cos^2 \alpha + \cos^2 \beta + \cos^2 \gamma - 2 \cos \alpha \...
3
votes
1
answer
839
views
On a combinatorial inequality
Is it true that
\begin{gather}
\min\left(\lambda_{\min}(M_{12}), \lambda_{\min}(M_{13}), \lambda_{\min}(M_{14}), \lambda_{\min}(M_{15}), \lambda_{\min}(M_{23}), \\ \lambda_{\min}(M_{24}), \lambda_{\...
3
votes
1
answer
227
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Handling absolute value and other discontinuities in numerical optimization methods that use gradients
Suppose we have difficult peak fitting problems where the the users wish to fit asymmetric peaks to their experimental data by the least squares method. One such function is illustrated below:
Here
$...
1
vote
0
answers
72
views
Inequality Involving Concave Monotonic Function
Assume that $ f: \mathbb{R} \to \mathbb{R}_+ $ is a concave, non-decreasing and positive function. Let $\mathbb{X}$ be a finite set consisting of $ 0\leq x_1 \leq x_2 \leq x_3 \leq \ldots \leq x_n$. ...
0
votes
0
answers
55
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A question on the optimisation problem and FWL theorem
Let's say we are considering the following model:
$$
(\beta^{\star},f^{\star}) := \arg\min_{\beta,f \in \mathcal{F}} \mathbb{E}[\left(Z_i - f(X_i, E_i) - \beta^\top \boldsymbol{\tau}_{i,E_i}\right)^2|...
0
votes
0
answers
90
views
A maximisation problem : finite or not?
Let $\mathcal M_2$ be the space of real $2\times 2$ matrices and $\mathcal S_2\subset \mathcal M_2$ be its subset consisting of positive semidefinite elements, i.e. $A\in \mathcal S_2$ iff $A$ is ...
1
vote
0
answers
82
views
Extension of this maximisation problem : finite or not?
$\mathcal M$ is the space of real $d\times d$ matrices and $\mathcal S\subset \mathcal M$ is its subset consisting of positive semidefinite elements. We consider the distance the product space $\...
2
votes
1
answer
96
views
$k$-subset with minimal Hausdorff distance to the whole set
Let $(\mathcal{M}, d)$ be a metric space. Let $k \in \mathbb{N}$. Let $[\mathcal{M}]^k$ be the set of $k$-subsets of $\mathcal{M}$. Consider the following problem:
$$ \operatorname*{argmin}_{\mathcal{...
2
votes
1
answer
301
views
Does this maximisation problem admit a finite upper bound?
Let $\mathcal M_2$ be the space of real $2\times 2$ matrices and $\mathcal S_2\subset \mathcal M_2$ be its subset consisting of positive semidefinite elements, i.e. $A\in \mathcal S_2$ iff $A$ is ...
0
votes
0
answers
96
views
How to formulate piecewise quadratic function optimization without introducing binary variables?
I have a problem with logical constraints (either-or constraints). I know that it can be solved by either big-M or complementary formulations. However, i do not want to convert it into mixed-integer ...
0
votes
0
answers
135
views
Minimizing the Spectral Norm of the Hadamard Product of a Quadratic Form Using CVX
I am trying to use CVX to minimize the spectral norm of the Hadamard product of two matrices, one of which is in quadratic form. Specifically, I am trying to minimize $\|{\bf A} \odot {\bf XX}^H\|_2$, ...