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Reichstag dome
The Reichstag dome is a glass and steel cupola by Norman Foster on the Reichstag Building in Berlin, open to visitors above the Bundestag chamber since 1999.
Reichwalde Coal Mine
The Reichwalde coal mine (Tagebau Reichwalde) is an open-cast lignite mine in Saxony, Germany, operated by LEAG and supplying the Boxberg power station since 1987.
Reid Hoffman
Reid Hoffman is an American technology entrepreneur and venture capitalist best known as the co-founder of LinkedIn, sold to Microsoft for $26.2 billion in 2016, and an early OpenAI investor.
Reihoku power station
Reihoku Power Station (苓北発電所) is a coal-fired power station in Reihoku, Kumamoto Prefecture, Japan, operated by Kyushu Electric Power with two 700,000 kW units commissioned in 1995 and 2003.
Reims Cathedral
Reims Cathedral (Cathédrale Notre-Dame de Reims) is the Gothic cathedral of Reims, France, built mainly in the 13th century and the coronation church of French kings.
Rein Ulijn
Rein V. Ulijn is a Dutch-born biomaterials scientist who directs the Nanoscience Initiative at CUNY's Advanced Science Research Center, known for enzyme-responsive peptide hydrogels and peptide discovery methods.
Reinaldo Augusto Valenzuela
Reinaldo Augusto Valenzuela is a Chilean-born wireless researcher who directs Wireless Communications Research at Nokia Bell Labs and was elected to the National Academy of Engineering in 2017.
Reiner Kirchheim
Reiner Kirchheim is a German metallurgist at the University of Göttingen, elected to the US National Academy of Engineering in 2017 for work on hydrogen in metals.
REINFORCE
REINFORCE is an early Monte Carlo policy-gradient algorithm in reinforcement learning, introduced by Ronald Williams in 1988, which updates policy parameters toward actions that led to high return.
Reinforced concrete
Reinforced concrete, or ferro-concrete, is a composite building material in which embedded steel bars carry the tension that concrete cannot resist, used in roads, bridges, and buildings.
Reinforcement fine-tuning (OpenAI)
Reinforcement fine-tuning (RFT) is OpenAI's post-training method that adapts reasoning models with reinforcement learning, using a customer-defined grader to score candidate responses; supported on o4-mini and, per Azure, gpt-5.
Reinforcement learning
Reinforcement learning (RL), also called reinforced learning, is the branch of machine learning where an agent learns behavior through trial and error to maximize cumulative reward.
Reinforcement learning for grasping
Reinforcement learning for grasping is the use of trial-and-error learning, where a robot improves picking skills from rewards for successful grasps rather than hand-programmed planners.
Reinforcement learning for legged locomotion
Reinforcement learning for legged locomotion uses reward-driven training in physics simulators to teach quadrupedal, bipedal, and humanoid robots to walk, run, and recover, a dominant approach since about 2018.
Reinforcement learning from AI feedback (RLAIF)
Reinforcement learning from AI feedback (RLAIF) is a model-training technique in which AI judges, usually large language models, replace human annotators in producing preference labels for reinforcement learning fine-tuning.
Reinforcement learning from human feedback (RLHF)
Reinforcement learning from human feedback (RLHF) is a post-training method for large language models that trains a reward model on human preferences, popularized in 2017 and used for ChatGPT.
Reinforcement learning from human feedback for robots
Reinforcement learning from human feedback (RLHF) for robots trains AI agents with human preferences, ratings, corrections, and demonstrations instead of hand-designed rewards, made prominent by Paul Christiano's 2017 work.
Reinforcement learning from verifiable rewards
Reinforcement learning from verifiable rewards (RLVR) is a post-training method for large language models in which the reward comes from programmatic checks, such as math answer checking or unit tests.
Reinforcement learning with verifiable rewards
Reinforcement learning with verifiable rewards (RLVR) is a post-training method for large language models whose rewards come from programmatic checkers like unit tests and answer matchers, named by the Tulu 3 paper in 2024.
Reinhard Woltman
Reinhard Woltman (also spelled Woltmann), born 1757 and died 1837, was a German hydraulic engineer who directed all of Hamburg's water engineering and invented the Woltman Flügel current meter for measuring flow in open channels.
Reinhardt Schuhmann Jr.
Reinhardt Schuhmann Jr. (1914–1996) was an American extractive metallurgist and Purdue University professor, elected to the National Academy of Engineering in 1976 and co-inventor of the QSL lead-smelting process.
Reinhold H. Dauskardt
Reinhold H. Dauskardt is a materials scientist who holds the Bowes Professorship at Stanford University, known for thin-film adhesion, perovskite solar cell manufacturing, and skin biomechanics.
Reinhold Rudenberg
Reinhold Rudenberg was a German-born electrical engineer who headed the scientific department at Siemens, filed the first electron microscope patents in 1931, and became a Harvard professor.
Reinjection geothermal
Reinjection geothermal is the practice of returning spent geothermal fluids, brine, and condensate into the subsurface reservoir, disposing of wastewater while replenishing the reservoir to sustain power generation.
REINVENT
REINVENT is an open-source molecular design tool developed at AstraZeneca that uses generative neural networks and reinforcement learning to create and optimize small molecules for drug discovery.
Reis telephone
The Reis telephone was an apparatus for electrical sound transmission built by teacher Johann Philipp Reis, presented in Frankfurt in 1861; it carried melodies but speech only in garbled fragments.
ReiserFS
ReiserFS is a journaling filesystem for Linux designed by Hans Reiser, the first general-use Linux filesystem to support journaling, known for tail packing and removed from the kernel in 2024.
Rejection sampling fine-tuning
Rejection sampling fine-tuning (RFT) trains a language model on its own filtered outputs: it samples many responses per prompt, keeps the correct ones, and fine-tunes on them.
Rejuvenation of bulk metallic glasses
Rejuvenation of bulk metallic glasses is the controlled raising of an amorphous alloy to a higher-energy state, improving its room-temperature plasticity without changing the alloy's composition.
Reka AI
Reka AI is an independent multimodal AI research lab in San Francisco, founded in 2022 by ex-DeepMind, Google, and Meta researchers and valued at $1 billion in 2025.