Tuesday, January 30, 2024

One nonzero in set of free variables

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In [1] the following question is posed: I have free variables \(\color{darkred}x_i\). How can I impose the constraint that at least one of t...
1 comment:
Tuesday, January 16, 2024

Informs Test of Time Award for CONOPT paper

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The Test of Time Award for papers published in the  INFORMS Journal on Computing  in the years 1993–1997 is awarded to CONOPT: A Large-Scale...
Monday, January 8, 2024

GAMS listing file: missing Unicode support

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Newer versions of GAMS allow UTF-8 encoded strings as labels. That is very welcome, as these labels may come from data sources that just use...
Thursday, January 4, 2024

String Art

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  In [1], a greyscale picture is approximated by strings (lines) between points around the image. Here, I will try something similar with a ...
Sunday, November 19, 2023

Grouping items: a difficult combinatorial problem

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In [1], a simple problem is described: We have \(n\) items (or orders) with a certain width.  We need to combine these items in groups (call...
4 comments:
Saturday, October 21, 2023

Scheduling Team Meetings

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This is a simple problem from [1]: I'm rusty on constraint optimization and am looking for help in this particular use case. There are i...
2 comments:
Friday, October 20, 2023

GAMS: SMAX and sparsity

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This is a discussion about the SMAX function in GAMS and how it behaves for sparse data. The data structure we were facing was something lik...
Thursday, October 19, 2023

Plotting NUTS-2 maps from GAMS

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 NUTS-2 regions are statistical subnational regions (often provinces), mainly for the EU and UK [1].  NUTS hierarchy (from [1]) In [2] we ca...
Thursday, October 5, 2023

Linear Programming Nonsense?

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1. Inventory balance constraints I came accross this text [1]: Inventory Balance Constraint
Wednesday, September 27, 2023

Math and ChatGPT

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Performing symbolic math steps is often related to pattern recognition. In theory, ChatGPT could be doing a good job here. I wanted to find ...
2 comments: