@TedRalphs

#Mastodon: @TedRalphs@sigmoid.social #BlueSky: @tedralphs.bsky.social Professor, Industrial and Systems Engineering, Lehigh University. Do math, write code.

 Bethlehem, PA
coral.ie.lehigh.edu/~ted
Joined August 2011
  • Tweets135
  • Following189
  • Followers740
14Media
CyLP has a new release that supports Numpy 2 for those who were waiting for that! As always, there are binary wheels for all platforms, thanks to #cibuildwheel! github.com/coin-or/CyLP/disc…

New Version 0.93.1 · coin-or CyLP · Discussion #221

A new version 0.93.1 was made from the master branch. With this update, we have added support for Numpy 2! There are binary wheels available for all platforms (see full list here). See here for cha...

github.com
2
3
609
Super happy to announce @nvidia 's cuOPT as an official @coin_or project: coin-or.org/2025/06/11/annou…

Announcing the Addition of NVIDIA cuOpt to the COIN-OR Repository

We are pleased to announce the addition of NVIDIA cuOpt to the COIN-OR repository on Github. cuOpt is an open source library implementing GPU-accelerated algorithms for optimization. The addition o…

coin-or.org
1
10
555
Excited to announce COIN-OR's collaboration with NVIDIA in open-sourcing cuOpt! coin-or.org/2025/03/18/the-c… blogs.nvidia.com/blog/cuopt-…

The COIN-OR Foundation Bridging New Frontiers in Open-Source Optimization with NVIDIA 

A New Chapter: COIN-OR and NVIDIA cuOpt Join Forces for Open-Source Optimization Optimization has always been at the core of computational research, and now, a new frontier is emerging—one where op…

coin-or.org
2
4
30
1,279
We're happy to announce the formation of the Bilevel Optimization Society! See the Website for a description and and bylaws: bileveloptimization.org. Register to become a member by filling in this form: forms.office.com/e/xa7m37UDc…. First elections coming soon, spread the word!
3
15
780
Absentee ballot received! Please vote!
2
377
Great working on this paper with my good friend Oleg Prokopyev, who came up with most of the deep ideas. Even if you have no interest in complexity, there's some good insight into the relationship between bilevel, quadratic, and combinatorial optimization. optimization-online.org/?p=2…
1
3
20
739
We reformulate the max clique problem as a bilevel optimization problem along the lines of Motzkin-Strauss and show that producing a locally optimal solution to a BLP is a combinatorial problem over bases of the lower level. The result is analogous to Ahmadi and Zhang's for QP.
2
205
Thrilled and honored to have been one of the speakers at the wonderful Fulkerson Centennial Celebration at Cornell with Jack Edmonds in the house! orie.cornell.edu/orie-events…
1
33
1,084
Thanks to my brilliant co-authors Samira Fallah and Natashia Boland, our paper detailing the close relationship between the efficient frontier of a multiobjective MILP and the so-called restricted value function of a related MILP has been accepted at MMOR. arxiv.org/abs/2303.00785
1
10
589
The upshot: constructing the RVF is equivalent to constructing the frontier. Exploiting this, we adapt our existing generalized cutting-plane algorithm for constructing the classical value function to the multiobjective MILP setting with an arbitrary # of objectives. Enjoy!
159
In support of @schmaidt 's #ISMP talk on the #BOBILib, here are some some newly minted results using the benchmark set with different versions of MibS over time. This includes the most recently released version 1.2.1 (github.com/coin-or/MibS/rele…), which I neglected to post about.
1
2
11
588
more replies
Here are the results over a much larger set of almost 700 instances, most of which are included in the current #BOBILib collection (the rest will be soon).
1
132
If you attend the session in which @schmaidt 's #ISMP talk is scheduled (WA231 — Bilevel Optimization with Discrete Decisions (I), going on now!), make sure you stick around for Federico Battista's talk about some even more recent attempts to improve performance of MibS!
119
My wife @Ke_Yang_ and co-authors have an interesting new paper about bias in LLMs.
⑆Luke Stein⑈@lukestein3 Jun 2024
Fresh WP: “Measuring and Mitigating Racial Bias in LLM Mortgage Underwriting” with Don Bowen, McKay Price, and Ke Yang Our audit study asks AI to assess simple mortgage applications (real HMDA data w/ randomized race and credit scores) 🦶🦶🏼🦶🏿 Download lukeste.in/llmbias 1/
Measuring and Mitigating Racial Bias in Large Language Model Mortgage Underwriting Donald E. Bowen III (Lehigh University) S. McKay Price (Lehigh University) Luke C.D. Stein (Babson College) Ke Yang (Lehigh University) We conduct an audit study of loan approval and interest rate decisions suggested by large language models (LLMs). Using a dataset of real loan applications and experimentally manipulated race and credit scores, we find that LLMs recommend denying more loans and charging higher interest rates to Black applicants than otherwise-identical white applicants. This racial bias is largest for lower-credit-score applicants and riskier loans, but present across the credit spectrum. Surprisingly, simply instructing the LLM to make unbiased decisions eliminates the racial disparity in approvals and moderates the interest rate disparity. … [Abstract text truncated due to Twitter's silly alt text character limits. Full text at lukeste.in/llmbias ]

ALT Measuring and Mitigating Racial Bias in Large Language Model Mortgage Underwriting Donald E. Bowen III (Lehigh University) S. McKay Price (Lehigh University) Luke C.D. Stein (Babson College) Ke Yang (Lehigh University) We conduct an audit study of loan approval and interest rate decisions suggested by large language models (LLMs). Using a dataset of real loan applications and experimentally manipulated race and credit scores, we find that LLMs recommend denying more loans and charging higher interest rates to Black applicants than otherwise-identical white applicants. This racial bias is largest for lower-credit-score applicants and riskier loans, but present across the credit spectrum. Surprisingly, simply instructing the LLM to make unbiased decisions eliminates the racial disparity in approvals and moderates the interest rate disparity. … [Abstract text truncated due to Twitter's silly alt text character limits. Full text at lukeste.in/llmbias ]

1
7
1,028
I'm very happy to announce my election as a Fellow of @INFORMS, which was formed the year I got my Ph.D! It's been great to "grow up" side-by-side and I am grateful for all the ways it has contributed to my own evolution as a researcher and a human. engineering.lehigh.edu/news/…

Lehigh ISE faculty Ted Ralphs has been elected a Fellow of INFORMS

Lehigh ISE Professor Ted Ralphs has been elected a Fellow of the Institute for Operations Research and the Management Sciences (INFORMS). This honor is reserved for few select members of INFORMS, and...

engineering.lehigh.edu
13
98
10,693
I'm really excited to announce version 1.2.0 of MibS, our solver for bilevel mixed integer linear optimization. There are a lot of of improvements, especially to usability and out-of-the-box performance. github.com/coin-or/MibS/rele….

Release Release releases/1.2.0 · coin-or/MibS

github.com
1
6
41
2,449
more replies
Here are some URLs in case you're interested: ALPS (github.com/coin-or/CHiPPS-AL…), BiCePS (github.com/coin-or/CHiPPS-Bi…), and BLIS (github.com/coin-or/CHiPPS-BL…).

GitHub - coin-or/CHiPPS-ALPS: This is the Abstract Library for Parallel Search (ALPS), the abstract...

This is the Abstract Library for Parallel Search (ALPS), the abstract base layer of the COIN-OR High Performance Parallel Search framework. - coin-or/CHiPPS-ALPS

github.com
1
4
328
A tech report discussing the source of the improvements in depth is due out anytime, so stay tuned!
2
264
Load more