Jeff Shrager writes a comprehensive guide to Herbert Simon's 1961 Heuristic Compiler, a program that uses General Problem Solver (GPS) means-end analysis to generate IPL-V code. After being dormant for roughly 65 years, the archival card deck was transcribed and successfully run on a modern Common Lisp interpreter. The system is composed of three parts: a State Description Compiler that derives code from before-and-after memory states, a Functional Description Compiler that modifies existing code based on imperative phrases, and a General Compiler executive that manages the search process. Notably, the program reproduces the exact machine code printed in Simon's 1963 paper, such as the "INSERT AT END OF VALUE LIST" and "SET SIGNAL MINUS" examples, without any modern language rewrites.
- The guide highlights that the compiler treats routine generation as a problem to be solved via operator search rather than a direct translation task.
- A debugging print statement left in routine U113 happens to output the exact stage-by-stage compilation sequence described in the 1963 paper.
- The original 1961 deck fails to compile the J3 routine; a specific card must be modified to erase a redundant description before the state compiler can execute successfully.
- The guide highlights that the compiler treats routine generation as a problem to be solved via operator search rather than a direct translation task.
- A debugging print statement left in routine U113 happens to output the exact stage-by-stage compilation sequence described in the 1963 paper.
- The original 1961 deck fails to compile the J3 routine; a specific card must be modified to erase a redundant description before the state compiler can execute successfully.
The Large Hadron Collider (LHC) has entered Long Shutdown 3 (LS3), marking the end of a significant operational era and the beginning of a major upgrade phase. This period involves extensive maintenance, such as replacing 1.2 kilometers of magnets, to prepare for the High-Luminosity LHC (HiLumi LHC). Scheduled to begin operation in 2030, the HiLumi LHC aims to increase luminosity tenfold, allowing for more precise studies of the Higgs boson and other fundamental particles. During the shutdown, experiments like ATLAS and CMS will undergo significant detector upgrades to manage increased collision rates.
- Transition to the High-Luminosity LHC (HiLumi LHC)
- Major maintenance and magnet replacement projects
- Extensive upgrades to ATLAS and CMS detectors
- Continued scientific research through data analysis
- Transition to the High-Luminosity LHC (HiLumi LHC)
- Major maintenance and magnet replacement projects
- Extensive upgrades to ATLAS and CMS detectors
- Continued scientific research through data analysis
This article is a survey of the history and ideas of gauge theory. It discusses the emergence of symmetry, Noether’s theorem, the gauge principle, and the role of gauge fields in mediating interactions. It also examines the electromagnetic field and generalizations to non-Abelian gauge theories, concluding with a look at the dream of total unification.
Tables once ruled web design, with nested tables causing both creativity and chaos. Replaced by CSS for layouts, they’re now a nostalgic tool still essential for data.
