# Questions tagged [findinstance]

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### Find a non-convex instance for a non-convex set function with FindInstance

Let $f$ be a non-convex set function defined on a set $L$. Hence there are subsets $A,B\subseteq L$ such that $$f(A)+f(B)>f(A\cup B)+f(A\cap B).$$ I tried to use FindInstance function to find a non-...
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### Obtain fairly sampled data set subject to a condition?

I need to obtain a random distribution of some parameters {t1,t2,t3} subject to a set of conditions. For example, ...
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### FindInstance taking too long

I just started to use Wolfram Alpha Notebook Edition. I am using FindInstance command to evaluate the sign of an expression with $8$ variables, under simple constraints, but it takes too much time. Do ...
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### Why does specifying the solution domain seriously affect the solution speed?

I want to solve the problem of this post. After trying, I found a strange problem. When I specify the solution field as a real field, the code runs all the time: ...
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### My Program using NSolve and FindInstance has been running for days without a solution

I have a system of 5 non-linear equations and 5 unknowns (p1,p2,p3,p4,p5 bellow), and a few inequalities. I am trying to understand whether the solution is unique. For this purpose, I tried to run ...
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### How can I find some values for which an expression is real?

I've a complicated expression which depends on several variables. I want to find some values for those variables such that the complicated expression is real. How can I do that? The obvious command ...
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### Turning FindInstance into True or False

I have a function where I input a certain vector of parameters and it gives me the output of 16 FindInstances. So, a typical output will look something like this ...
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### Finding a solution to a modular problem efficiently

I want to find a naïve hash function of the form Mod[a x + b, 2^p] which would produce a value less or equal to v for all ...
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### Why does FindInstance take so long: It is faster with more restrictions than with less?

A support case with the identification [CASE:4347836] was created. I just noted this little puzzle on twitter by Brillant.org: \begin{align} A B C\\+ BCA\\ = CDE \end{align} Given that $A$ is even ...
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### FindInstance confused by CoprimeQ

For some reason when I type FindInstance[a + b == c && CoprimeQ[a, b, c] == True, {a, b, c}, Integers] Mathematica just immediately returns my input as ...
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### FindInstance Returns “Aborted” [closed]

Edit: Apologies, the question needs to be reworked, because I cannot reproduce the original problem using this code. I don't delete the question, in case someone is preparing an answer at the moment. ...
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### How to use a given list of values for a parameter in FindInstance?

How should I specify a discrete range for a parameter as one of the conditions in FindInstance? MemberQ/Element functions don't seem to work. For example, ...
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### FindInstance with a symbolic constant

Please consider FindInstance[m >= 0 && x >= 0 && x <= m, {x}] for which, I would like a parametric answer ...
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### FindInstance within a range

I am trying to find particular solutions to my inequality for two positive integers $a$ and $b$: FindInstance[a<f[etc...]*b,{a,b},Integers] However I want $a$ ...
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### Checking Rationality Using FindInstance

I need to find example if $x,\sqrt{x^2+6},\sqrt{x^2+12}$ all can be rational at once or not. But the following command ...
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### Problems with FindInstance in v. 11

I have been trying to solve a system of linear equations and linear inequalities with 18 unknowns. I would think that for Mathematica giving an answer to such question will be a matter of milliseconds....
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### solving linear systems with parameters

I am trying to solve simple, small linear systems, with parameters. I would like to have the result shown for various values of the parameter. RowReduce[], ...
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### What is the algorithm used in FindInstance? [closed]

Is FindInstance guaranteed to find an instance if one exists? Conversely, if it does not find an instance, does that mean an instance does not exist at all? Finally, is there a way to change the ...
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### Faster way to pick pairs of integer coordinates from a “region”

I am trying to find a faster way to do this than what I have put together or by looping through a bunch of points. I want to select all pairs of integer points ((x1,y1),(x2,y2)) such that: Point (x1,...
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### Get a feasible solution

Link : Reduce time taken to get feasible solution I have 18 inequations with 4 variables vars2 = {arb, arb, arb, arb} , To get a feasible solution, NMinimize and Nmaximize were used as ...
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### Error using NMinimize/NMaximize : The initial region specified may not contain any feasible points

Link : Reduce time taken to get feasible solution An example of 18 non linear inequations with 4 variables is given in the image. But I have a set of 32 non linear inequations with 9 variables (I ...