# Possible bug in Surrogates.jl RTEA

**URL:** <https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524>\
**Category:** General Usage\
**Tags:** package\
**Created:** [January 8, 2025, 6:49am UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524 "2025-01-08T06:49:20Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![ij05](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ij05/32/209328_2.png) [@ij05](https://discourse.julialang.org/u/ij05)\
**Post date:** [January 8, 2025, 6:49am UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/1 "2025-01-08T06:49:20Z")

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Hi,  
This is regarding a discrepancy that I have noticed while using the Surrogates.jl RTEA optimizer. I am not sure if this is the right medium to discuss regarding the same. Please let me know.  
I was going through the code of the RTEA optimizer:  
The mutated solutions according to lines: 1882 ans 1883 are labelled as “x\_new” and “y\_new”. But when they are added back to the surrogate model, they are labelled as “new\_x” and “new\_y.” Is this a mistake, or have I got it completely wrong?  
Looking forward to the responses.

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [January 8, 2025, 7:15am UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/2 "2025-01-08T07:15:19Z")

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Can you open an issue in the repo? This isn’t the place for bug reports.

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**Author:** ![ij05](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ij05/32/209328_2.png) [@ij05](https://discourse.julialang.org/u/ij05)\
**Post date:** [January 8, 2025, 7:30am UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/3 "2025-01-08T07:30:32Z")

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Ok, I shall open an issue.  
Thanks

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**Author:** ![ij05](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ij05/32/209328_2.png) [@ij05](https://discourse.julialang.org/u/ij05)\
**Post date:** [January 8, 2025, 2:03pm UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/4 "2025-01-08T14:03:37Z")

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@ChrisRackauckas,  
Are there any research papers or pointers regarding the SMB optimization algorithm that you could share?  
Thank you

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [January 8, 2025, 4:48pm UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/5 "2025-01-08T16:48:22Z")

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Those should be referenced in the original PR. It is hard to search for that on my phone but all links are in the GitHub issues and PRs on the topic

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**Author:** ![ij05](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ij05/32/209328_2.png) [@ij05](https://discourse.julialang.org/u/ij05)\
**Post date:** [January 8, 2025, 5:23pm UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/6 "2025-01-08T17:23:52Z")

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Thanks for the reply.  
I was able to find the paper on [RTEA](https://ieeexplore.ieee.org/abstract/document/6730915), but couldn’t find anything on the SMB multi-objective opt. from the PR or Github issues.

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [January 22, 2025, 6:11pm UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/7 "2025-01-22T18:11:25Z")

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Interesting, I’d have to dig around. Can we bring this discussion to an issue so it doesn’t get lost?

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**Author:** ![ij05](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ij05/32/209328_2.png) [@ij05](https://discourse.julialang.org/u/ij05)\
**Post date:** [January 23, 2025, 3:59am UTC](https://discourse.julialang.org/t/possible-bug-in-surrogates-jl-rtea/124524/8 "2025-01-23T03:59:35Z")

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I have raised an [issue](https://github.com/SciML/Surrogates.jl/issues/504).  
Thank you.