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Questions tagged [constraints]

In mathematics, a constraint is a condition of an optimization problem that the solution must satisfy.

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Characterize candidates for absolute extrema with Lagrange multiplier for equality constraint

When we are looking for absolute extrema in a closed interval in basic calculus, the candidates for extrema lie in $A \bigcup B \bigcup C$ where $A$ is the set of points where derivative ...
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CPLEX candidate solutions ignore lazy constraints

Whilst generating lazy constraints through my custom IloCplex.Callback.Function, I encounter the following behaviour: After identifying ‘valid’ lazy constraints A, for one candidate X my heuristic ...
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Why is the constraint $\mbox{rank} (X) \leq r$ non-convex?

I have a problem claiming that the set of solutions of the minimization problem of a convex objective function on this rank constraint is non-convex since the constraint is non-convex. Note that $X$ ...
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31 views

Constraint formulation that include consecutive values in an optimization problem

I am currently lost in finding a way on how to mathematically formulate a constraint within the following problem: I want to allocate some water tanks locations within a network, which size will vary ...
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54 views

Missing Constraint for VRP with Time Schedules

Cross-posted at Operations Research SE I am trying to model a VRP with time schedules. The objective is to minimize the cost of vehicles used and routing. There are "activities" on the nodes that ...
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35 views

Cauchy problem and boundary conditions in electromagnetism

Consider a connection on a principal $U(1)$-bundle $A_\mu$ over the flat base manifold $M_4$. The action of the theory is described in terms of the curvatures of such connection coupled to some source ...
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Statistics with Fisher formalism : loss or gain of information with data cross-correlations

I am currently working on Fisher's formalism which is part of a more general theory, that of information. My problem applies to estimating cosmological parameters from input data with the Fisher ...
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11 views

Restricted Weighted Linear Regression in R

I have to follwing issue. I would like to run a linear regression imposing a constraint on the weighted coefficients. Let me construct an example: Consider the following cross-sectional regression $...
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30 views

Convexifying the biconvex constraint $xy-f(x,y)=0$ to $\max f(x,y)$

I want to solve $$\min_{x,y} \quad -f(x,y) \qquad \text{subject to} \quad xy C - f(x,y)K -\kappa = 0$$ where $x, y$ are from a compact and convex subset of $\mathbb{R}^2$ $f(x,y)$ is concave, in $...
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Multivariate Optimization over Lotteries

I have the following maximization problem. $\max\limits_{x,y,Pr(s)} E[xy]$ s.t. $E[(x(1-p)+y(1+p)-x^2-y^2)C - p^3)- Z xy] = 0$ where $1>Z,C,p>0$ are constants and $0<p\leq x\leq y<1$....
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How can I linearize the IFF-THEN constraint with binary and continuous variable?

I have an optimization problem where $a_{m,n}\in\{0,1\}$ is a binary variable and $0\le f_{m,n}\le 1$ is a continuous vaiable I have an Iff-THEN constraint like this IFF $a_{m,n}=1$, THEN $f_{m,n}&...
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Lagrange multipliers - confused about when the constraint set has boundary points that need to be considered

Consider the constraint $$S_1 = \{(x, y) \; |\; \sqrt{x} + \sqrt{y} = 1 \}$$ How to use Lagrange Multipliers, when the constraint surface has a boundary? In this case, after the Lagrange multiplier ...
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45 views

Solving for integrand from integrated quantities.

Given equations of the form: $A(r) = \int_{t_{1}}^{t_{2}}F(r,t)dt$ $B(t) = \int_a^b F(r,t)r^2dr$ where $A(r)$, $B(t)$, and all of the limits on the integrals are known, is there enough information ...
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How is the inequality constraint $\mbox{Tr}(W) \geq c$ convex?

In one paper, I found that the following inequality constraint $$\mbox{Tr}(W) \geq c$$ where $W$ is a symmetric positive semidefinite matrix variable and $c$ is a constant, is convex. In my ...
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Formulation of SVM optimization problem

I need help in verifying/understanding a step in formulating an optimization problem used for support vector machines (though this question doesn't need any background in SVM). Consider a bunch of $m$ ...
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35 views

Formulation of a constrained optimization problem with probabilities

we are given four probabilities for an event. We shall adapt these probabilities in order to maximize the entropy given a constraint $4 = \sum_{i = 1}^4 2p_ii \Leftrightarrow 2 = \sum_{i = 1}^4 p_ii$. ...
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Periodic B-spline least squares fitting

I have a set of $M$ data points $(x_j,y_j), 1 \le j \le M$ defined on an interval $[a,b]$ and I want to fit a periodic B-spline of order $k$ to these data. So my model will be: $$ f(x) = \sum_{i=1}^N ...
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Lagrange multipliers example with sympy - all minima but one maxima.

Consider the following optimization problem: Minimize $x^3+y^3$ Subject to: $x^2+y^2 \leq 1$ On the boundary of the constraint, we can consider $x=\cos\theta$ and $y=\sin\theta$. Then, the ...
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Similarity of the solutions

I am trying to solve the following rank-k decomposition $$\Sigma \approx W\Lambda W^T$$ where $\Sigma \in R^{n \times n}$ is a positive definite symmetric matrix having diagonal elements 1, $\Lambda \...
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Given a circle $A$ of area 1 centered at $\{0,0\}$, give conditions that another circle $B$ of known area <1, lies totally within $A$

Given a circle $A$ of area 1 centered at $\{0,0\}$--so, of radius $\frac{1}{\sqrt{\pi}}$--give conditions on the possible location of the center $\{x,y\}$ of another circle $B$ of known area $\pi r^2 &...
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Convex Conjugate of sum-of-max terms

Let $f: \mathbb{R}^n \mapsto \mathbb{R}$ be a sum-of-max linear terms function: $$f(x) = \sum_{k=1}^K \max_i\{a_{k,i}^\top x\}$$ where $a$ are the linear coefficients. I am interested in the convex ...
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Optimizing a function under strictly positive constraint

Find x and y that optimise \begin{align} f(x,y) &= (-a-y)(\Psi(y)-\Psi(x+y)) + (b-x)(\Psi(x)-\Psi(x+y)) \\ &-\log \Gamma(x+y) + \log\Gamma(x) + \log\Gamma(y) \end{align} where a, b are ...
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Is there an easy way to tell if a set of quadratic constraints are solvable

I am trying to find a matrix whose null space $N\in\mathbb{R}^{9 \times n}$ does not intersect with the column space of the matrix $$ M(R) = \begin{bmatrix} 0 & -r_3 & r_2 \\ r_3 & 0 &...
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1answer
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Constants of motion for a system of two points moving on spherical surface with a force depending only on their relative distance

Consider two points that moves only on a spherical surface of radius $R$. There is only a force between them that has a potential $U(d)$ where $d$ is the distance between the two points. What is the ...
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1answer
21 views

Write logical operator all(x<a) in terms of Heavyside functions

I am currently solving a complex optimisation problem, with constraints that take the form: $1 - all(g(x)<a) <= 0$, meaning I require all values $g(x)$ (for some function $g$) to be below some ...
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23 views

Optimize for a parameter in a function with constraints on other 2 more parameters

I am an applied statistics student trying to solve a problem where constrained optimization is required. I have a function $f(x, p_1, p_2)$ in which $p_1 \epsilon [0,1]$, $p_2 \epsilon [0,1]$ are ...
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2answers
60 views

Least Squares with equality and inequality constraints

Could someone kindly suggest a method of solving the following constrained (equality and inequality) system of equations in the least squares fashion? $$\min_x\frac 12\|Ax-b\|_2^2$$ such that $$\...
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Degrees of freedom in hypothesis testing with multiple constrained parameters in one constraint

Suppose you are estimating a (multivariate) model with a parameter vector $\theta=(\theta_1,\dots,\theta_p)'$. You have two constraints in the model, and would like to test them with either the ...
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Solving/minimizing $Fw=b$ with $F$ and $w$ unknown and $b$ known

I have a system $Fw=b$ that can be underdetermined, square or overdetermined. The matrix $F$ contains known scalar functions $f_i(t)$ evaluated at unknown values $t_j$. The vector $w$ contains unknown ...
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46 views

Maximum and minimum of $\frac13x^3 - \frac32y^2 + 2x $ such that $x-y=0$

The function to maximize and minimize is; $$f(x,y) = \frac13x^3 - \frac32y^2 + 2x $$ The constraint is; $$g(x,y) = x-y $$ such that $$g(x,y) = 0$$ I found the first order condition and found ...
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Adding $\lambda\cdot d$ to a constraint. How does the optimal solution change?

We are give a linear programm in standard form. Given $A\in\mathbb{R}^{n}\times\mathbb{R}^{m}$ with Rank$(A)=m$ and $B$ a basis whos basis solution is optimal. Now the right side of the constraint $Ax=...
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Optimization, Are all points feasible if there is only one constraint?

The definition of a regular point is as follows : If instead of having multiple constraints there is only one, we would have $$ D\;h(x) = \nabla h_1(x)^T $$ Would all points then be regular ...
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Counting the number of variables and constraints

An optimization problem is defined a graph of V nodes and E edges. First, I defined variables on each nodes (two independent variables for each node), and each edge imposes one constraint (on the 2 ...
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Linearization of constraints including product of binary variables.

I have three constraints including product of binary variables as following: enter image description here So basically, I have a complicated multiplication of binary variables. I am wondering if I ...
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1answer
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Optimisation - first order necessary conditions, directions, Chong & Zak Q. 6.16

For this question from Introduction to optimisation by Chong & Zak : The answer is : I'm unsure about what's been done for part (b) here. From part (a) it seems that for $d$ we have $d=...
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Is there any online nonlinear constrained optimizor available?

I am trying to a nonlinear constrained optimization that has around 100 variables and countless constraints, is there any online nonlinear constrained optimizer available?
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1answer
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Proving $\frac12 < \int_0^1 \frac1{\sqrt{4-x+x^3}} dx < \frac{ \pi }6$

I have a question where I have to show $$\frac12 < \int_0^1 \frac1{\sqrt{4-x+x^3}} dx < \frac{ \pi }6 \approx 0.52359$$ using the result $$\frac12 < \int_0^{1/2} \frac{1}{\sqrt{1-x^{2n}}} ...
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Linear program geometry

I’ve tried to solve a question in my homework, and I don’t really know what to do. In the problem a polyhedron is given and I need to build the set of constraints that defines this polyhedron. The ...
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1answer
33 views

Labeling nodes in a bipartite graph to satisfy edge constraints

I'm trying to find an algorithm for the following problem. Let $G$ be a bipartite graph. The edges in $G$ have labels $R$; each label $R(u, v)$ is an integer range $[a, b]$ with $a$ and $b$ being ...
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2answers
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Strict inequality logical implication in optimization problems

I have $ x \in \{0,1\}$ and $y \geq 0$ and I want to model that $x=1$ iff $y>0$, is this possible while keeping the constraint linear? Thanks. One part of the implication is easy $ y \leq Mx$. The ...
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26 views

N dimension random distribution with constraints

I am trying to draw $M$ random/semi-random numbers in $N$ dimensions applying some constraints. For instants I have a method that "selects" only the right points, but I am sure that it can be done ...
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53 views

Lagrange multipliers don't seem to work

Consider the following constrained optimization problem: $$ \min x^3+y^3 \\ \text{s.t.} x^2+y^2\leq 1 $$ From plotting this, the minima seems to be at $(-1,0)$ and $(0,-1)$. Now, the KKT conditions ...
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Ratio Calculation in Linear Programming?

i struggle a bit with ratio and fraction calculations, so im just looking for some explanation for dummies of this one. in linear programming, i have a ratio constraint of 6:5, of product A to ...
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Is there efficient Surface Walking method for optimization problems with equality constraint?

To my best knowledge, if we want to find the minimum of a function $f$ defined on a $d$-dimension manifold $M$ in $\mathbb{R}^n$, a.k.a an optimization problem with equality constraint, the most ...
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28 views

Optimization with a symmetric matrix constraint

I have a problem where I need to find the optimal $X\in S_{++}^n$ (i.e. $X$ is positive definite) for a strictly convex function $f(X)$. For what I understand, I need to assign a positive ...
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1answer
45 views

Linear programming constraints

How do I formulate a linear constraint using LP for the following? $$x_1 + x_2 + \cdots + x_n \geq 5$$ then $z$ takes a value of $1$, where $x_1, x_2, \dots, x_n, z \in \{0,1\}$.
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Why does the Lagrange multiplier $\lambda$ change when the equality constraint is scaled?

Consider the problem $$\begin{array}{ll} \text{maximize} & x^2+y^2 \\ \text{subject to} & \dfrac{x^2}{25} + \dfrac{y^2}{9} = 1\end{array}$$ Solving this using the Lagrange multiplier method,...
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Minimizing polynomial function over the standard simplex

I have the following optimization problem $$\begin{array}{ll} \text{minimize} & \displaystyle\sum_{i=1}^k x_i \prod_{j=1}^{i-1} (1-x_j)\\ \text{subject to} & \displaystyle\sum_{i=1}^k x_i = 1\...
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1answer
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Describing Constraints Using Linear Algebra (Convex Optimization)

I've been learning Convex Optimization but one thing that really confused me in class was how exactly to recast a given set of constraints in matrix form, so that it can be solved using CVX. For ...
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Riemannian Manifold for the Partial Doubly Stochastic Matrices

Excuses if my formulation is non-rigorous. I am not a mathematician by training. I have a constrained optimization problem where each of my matrix valued parameters lives inside the Birkhoff Polytope....