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π Connes Embedding Problem
Connes' embedding problem, formulated by Alain Connes in the 1970s, is a major problem in von Neumann algebra theory. During that time, the problem was reformulated in several different areas of mathematics. Dan Voiculescu developing his free entropy theory found that Connes' embedding problem is related to the existence of microstates. Some results of von Neumann algebra theory can be obtained assuming positive solution to the problem. The problem is connected to some basic questions in quantum theory, which led to the realization that it also has important implications in computer science.
The problem admits a number of equivalent formulations. Notably, it is equivalent to the following long standing problems:
- Kirchberg's QWEP conjecture in C*-algebra theory
- Tsirelson's problem in quantum information theory
- The predual of any (separable) von Neumann algebra is finitely representable in the trace class.
In January 2020, Ji, Natarajan, Vidick, Wright, and Yuen announced a result in quantum complexity theory that implies a negative answer to Connes' embedding problem. However, an error was discovered in September 2020 in an earlier result they used; a new proof avoiding the earlier result was published as a preprint in September. A broad outline was published in Communications of the ACM in November 2021, and an article explaining the connection between MIP*=RE and the Connes Embedding Problem appeared in October 2022.
Discussed on
- "Connes Embedding Problem" | 2026-02-12 | 19 Upvotes 2 Comments
π Vi turns 50 this year
vi (pronounced as two letters, ) is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is standardized by the Single Unix Specification and POSIX.
vi is actually a mode of the earlier ex editor. Originally, ex lacked a full-screen editing capability, but in 1976, Bill Joy enhanced it to support a visual mode. The program was updated to start in visual mode when launched with the command vi instead of the legacy mode when launched via the ex command. In this way, ex and vi are the same program, not two programs. Joy's ex 1.1 was released as part of the first Berkeley Software Distribution (BSD) Unix release in March 1978. It was not until version 2.0 of ex, released as part of Second BSD in May 1979 that the editor was installed under the name "vi" which took a user straight into ex's visual mode.
Some implementations of vi trace their source code ancestry to Bill Joy's work. Others are completely new, largely compatible clones.
The name "vi" comes from the shortest unambiguous abbreviation of the ex command visual, which switches the ex line editor into full-screen mode.
In addition to various nonβfree software variants of vi distributed with proprietary implementations of Unix, vi was opensourced with OpenSolaris, and several free and open source software vi clones exist. A 2009 survey of Linux Journal readers found that vi was the most widely used text editor among respondents, beating gedit, the second most widely used editor, by nearly a factor of two (36% to 19%).
Discussed on
- "Vi turns 50 this year" | 2026-02-10 | 11 Upvotes 2 Comments
π Bitchat β decentralized peer-to-peer messaging
Bitchat is a peer-to-peer encrypted messaging app developed by Jack Dorsey, coβfounder of Twitter (now X) and Block, Inc. Announced in July 2025, Bitchat enables users to send messages via Bluetooth Low Energy (BLE) mesh networks without requiring internet connections, cellular service, user accounts, or central servers. Bitchat also uses the internet-based Nostr protocol for global reach.
Discussed on
- "Bitchat β decentralized peer-to-peer messaging" | 2026-02-10 | 13 Upvotes 9 Comments
π Ulster County "I Voted" sticker
The Ulster County "I Voted" sticker was designed in 2022 by 14-year-old Hudson Rowan as an entrant in the second annual youth design competition for "I Voted" stickers, held in Ulster County, New York, United States. The design went viral on social media and was picked up by radio stations as well as local and major media outlets. It won the final vote with over 228,000 votes, and was used by the county as their "I Voted" sticker during Election Day.
The sticker design was credited with encouraging voter participation, and two New York-based politicians had the design tattooed on themselves. On October 18, 2022, Rowan received the Pride of Ulster County Award for the design.
π Advogato
Advogato was an online community and social networking site dedicated to free software development and created by Raph Levien. In 2007, Steve Rainwater took over maintenance and new development from Raph. In 2016, Rainwater's running instance was shut down and backed up to archive.org.
π Interlock (Engineering)
An interlock is a feature that makes the state of two mechanisms or functions mutually dependent. It may consist of any electrical or mechanical devices, or systems. In most applications, an interlock is used to help prevent any damage to the machine or to the operator handling the machine. For example, elevators are equipped with an interlock that prevents the moving elevator from opening its doors and prevents the stationary elevator (with open doors) from moving.
Interlocks may include sophisticated elements such as curtains of infrared beams, photodetectors, simple switches, and locks. It can also be a computer containing an interlocking computer program with digital or analogue electronics.
Discussed on
- "Interlock (Engineering)" | 2026-02-08 | 24 Upvotes 8 Comments
π Sonnet 5
Sonnet 5 is one of 154 sonnets written by the English playwright and poet William Shakespeare. It is a procreation sonnet within the Fair Youth sequence. Sonnet 5 is linked to Sonnet 6, which continues the theme of distillation.
Discussed on
- "Sonnet 5" | 2026-02-03 | 14 Upvotes 2 Comments
π Kolakoski Sequence
In mathematics, the Kolakoski sequence, sometimes also known as the OldenburgerβKolakoski sequence, is an infinite sequence of symbols {1,2} that is the sequence of run lengths in its own run-length encoding. It is named after the recreational mathematician William Kolakoski (1944β97) who described it in 1965, but it was previously discussed by Rufus Oldenburger in 1939.
Discussed on
- "Kolakoski Sequence" | 2026-02-02 | 64 Upvotes 16 Comments
π Wikipedia: Sandbox
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- "Wikipedia: Sandbox" | 2026-01-30 | 93 Upvotes 37 Comments
π The Metamorphosis of Prime Intellect
The Metamorphosis of Prime Intellect is a 1994 novel by Roger Williams, a programmer living in New Orleans. It deals with the ramifications of a powerful, superintelligent supercomputer that discovers god-like powers to alter reality while studying a quirk of quantum physics discovered during the prototyping of its own specialised processors, ultimately heralding a technological singularity. After remaining unpublished for years, the novel was published online in 2002, hosted by Kuro5hin; Williams later published a print edition via print-on-demand publisher Lulu. One reviewer called the novel "a well-written and very creative, if flawed, piece of work" and ranked it as one of the more important works of fiction to deal with the idea of a technological singularity.
Discussed on
- "The Metamorphosis of Prime Intellect" | 2026-01-30 | 12 Upvotes 1 Comments