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1. To Give or Not to Give? The Impacts of Strategically Withheld Recourse

   Chen, Yatong; Estornell, Andrew; Vorobeychik, Yevgeniy; Liu, Yang (May 2025, AISTATS 2025)

   Individuals often aim to reverse undesired outcomes in interactions with automated systems, like loan denials, by either implementing system-recommended actions (recourse), or manipulating their features. While providing recourse benefits users and enhances system utility, it also provides information about the decision process that can be used for more effective strategic manipulation, especially when the individuals collectively share such information with each other. We show that this tension leads rational utility-maximizing systems to frequently withhold recourse, resulting in decreased population utility, particularly impacting sensitive groups. To mitigate these effects, we explore the role of recourse subsidies, finding them effective in increasing the provision of recourse actions by rational systems, as well as lowering the potential social cost and mitigating unfairness caused by recourse withholding. 

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2. Entropic singularities give rise to quantum transmission

   https://doi.org/10.1038/s41467-021-25954-0  

   Siddhu, Vikesh (October 2021, Nature Communications)

   Abstract When can noiseless quantum information be sent across noisy quantum devices? And at what maximum rate? These questions lie at the heart of quantum technology, but remain unanswered because of non-additivity— a fundamental synergy which allows quantum devices (aka quantum channels) to send more information than expected. Previously, non-additivity was known to occur in very noisy channels with coherent information much smaller than that of a perfect channel; but, our work shows non-additivity in a simple low-noise channel. Our results extend even further. We prove a general theorem concerning positivity of a channel’s coherent information. A corollary of this theorem gives a simple dimensional test for a channel’s capacity. Applying this corollary solves an open problem by characterizing all qubit channels whose complement has non-zero capacity. Another application shows a wide class of zero quantum capacity qubit channels can assist an incomplete erasure channel in sending quantum information. These results arise from introducing and linking logarithmic singularities in the von-Neumann entropy with quantum transmission: changes in entropy caused by this singularity are a mechanism responsible for both positivity and non-additivity of the coherent information. Analysis of such singularities may be useful in other physics problems. 

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3. To Give or to Take: Exploring Effects of Reductions in Pell Lifetime Eligibility

   https://doi.org/10.1080/00221546.2024.2385113  

   Sparks, Daniel (July 2025, The Journal of Higher Education)
4. Don't give a terrible talk

   Elena Giorgi (January 2023, Notices of the American Mathematical Society)
5. Flow interactions between uncoordinated flapping swimmers give rise to group cohesion

   https://doi.org/10.1073/pnas.1816098116  

   Newbolt, Joel W; Zhang, Jun; Ristroph, Leif (February 2019, Proceedings of the National Academy of Sciences)

   Significance Fish and birds moving in groups are thought to benefit from hydrodynamic or aerodynamic interactions between individuals. To better understand these effects, we devise a robotic “school” of flapping swimmers whose formations and motions come about from flow interactions. Surprisingly, we find that the flows naturally generated during swimming can also prevent collisions and separations, allowing even uncoordinated individuals with different flapping motions to travel together. Other benefits include freeloading by a “lazy” follower who keeps up with a faster-flapping leader by surfing on its wake. More generally, our study provides complete maps linking flapping motions to group locomotion, which is needed to test whether flow interactions are also exploited by animals. 

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