All articles starting with R
22,461 articles
Representation theory of semisimple Lie algebras
The representation theory of semisimple Lie algebras, or Cartan–Weyl theory, classifies how semisimple Lie algebras act linearly on vector spaces, with every irreducible determined by its highest weight.
Representation theory of SL2(R)
The representation theory of SL2(R), the non-compact simple Lie group of 2 × 2 real matrices with determinant 1, studies its unitary representations, classified by Bargmann in 1947 into principal, complementary, and discrete series.
Representation theory of SU(2)
The representation theory of SU(2) classifies how the special unitary group SU(2) acts on vector spaces, with irreducibles labeled by spin and dimension 2s + 1.
Representation theory of the Galilean group
The classification of how the Galilei group, the nonrelativistic space-time symmetry group, acts on quantum systems; its ray representations, classified by Bargmann in 1954, carry mass as a central charge.
Representation theory of the Lorentz group
The representation theory of the Lorentz group studies how Lorentz transformations act linearly on vector spaces, dividing into non-unitary finite-dimensional representations for classical fields and unitary representations for particles.
Representation theory of the symmetric group
The representation theory of the symmetric group (S_n) studies how permutations act on vector spaces; its irreducible representations, the Specht modules, are indexed by integer partitions of n.
Representational similarity analysis
Representational similarity analysis is a neuroimaging method, introduced by Nikolaus Kriegeskorte in 2008, that characterizes brain representations by pairwise dissimilarities among activity patterns, enabling comparisons across species and models.
Representations
Representations is a quarterly peer-reviewed academic journal published by the University of California Press since 1983, publishing interdisciplinary humanities essays on culture and described as a leading journal in interpretive social sciences.
Representative agent
The representative agent is a hypothetical household or firm whose choices stand in for an entire economy, tracing to Alfred Marshall's representative firm and foundational to DSGE macroeconomic models.
Representative Concentration Pathway
A Representative Concentration Pathway (RCP) is one of four greenhouse gas and land use scenarios used in climate modeling, named for its radiative forcing by 2100.
Representative democracy
Representative democracy: citizens elect politicians who make decisions on their behalf. Covers delegate versus trustee roles (Madison, Burke, Pitkin, Rehfeld), origins in England and Poland from 1493, delegation and accountability theory, and 2023-2024 global survey data on support and trust.
Representative Men
Representative Men is an 1850 book by American essayist Ralph Waldo Emerson, published in Boston, arguing that great men like Shakespeare and Napoleon let ordinary people see themselves.
Representativeness heuristic
Representativeness heuristic: judgment of probability by resemblance to a category prototype, proposed by Kahneman and Tversky (1972); produces base-rate neglect, sample-size neglect, and the conjunction fallacy, and differs from the availability heuristic, which judges by ease of recall.
RepresentUs
RepresentUs is a nonpartisan American grassroots anti-corruption and democracy reform organization founded in 2012 by Josh Silver and Joshua Graham Lynn, based in Florence, Massachusetts, known for state and local ballot wins including South Dakota's first statewide Anti-Corruption Act and Michigan's independent redistricting commission; current CEO Maria McFarland Sánchez-Moreno.
Repressed memory
Repressed memory: the Freudian concept that trauma can be unconsciously blocked and later recovered, central to the 1990s memory wars; contested by false-memory research, with dissociative amnesia as its substitute term.
Repressor
Repressor: DNA-binding protein that decreases gene expression by blocking transcription; founding example is the lac repressor of Jacob and Monod (1961), basis of negative gene regulation, operon model, and 1965 Nobel Prize.
Repressor of RNA polymerase III transcription Maf1
Maf1 (MAF1) is the conserved global repressor of RNA polymerase III transcription, regulating tRNA and 5S rRNA synthesis via phosphorylation-controlled nuclear localization through TORC1, PKA, and PP4/PP2A signaling.
REPRIEVE trial
REPRIEVE (Randomized Trial to Prevent Vascular Events in HIV, NCT02344290) is a phase 3 NIH-funded trial of 7,769 people with HIV showing pitavastatin 4 mg daily reduced major adverse cardiovascular events by 35% versus placebo, driving 2024 statin guidelines.
REPRINT trial
REPRINT trial (NCT06302569, EU CT 2024-511587-93-00): single-arm phase II study of pembrolizumab plus enfortumab vedotin in rare collecting duct and renal medullary kidney carcinoma, 23 patients, primary endpoint objective response rate, Milan sponsor.
Reprisal (TV series)
Reprisal is a 2019 Hulu action drama series created by Josh Corbin, starring Abigail Spencer as Katherine Harlow, a femme fatale seeking revenge on her brother's gang, the Banished Brawlers. One 10-episode season, canceled in 2020; distinct from the 2018 Bruce Willis film of the same name.
Reprisals against commentators on the Charlie Kirk assassination
Reprisals against commentators on the Charlie Kirk assassination were firings and investigations targeting those who spoke critically about the killing of conservative activist Charlie Kirk on September 10, 2025.
Reprise (cover tradition)
Reprise is the French term for a cover, any new version of a song from an existing original; broader than "cover", it is central to the chanson tradition.
Reprise Records
Reprise Records, American record label founded December 1960 by Frank Sinatra for artistic freedom, sold two-thirds to Warner Bros. on August 3, 1963; Mo Ostin built it, now a Warner Records Group imprint led by Jeff Sosnow.
Reprocessed uranium
Reprocessed uranium (RepU; Uranium de Retraitement) is uranium recovered from spent nuclear fuel by chemical reprocessing. It comprises about 95% of used fuel mass and is recyclable.
Reprocessing plant
A reprocessing plant is an industrial nuclear facility that chemically treats spent fuel to separate reusable uranium and plutonium from waste, a process first developed in the 1940s.
Reproducibility
Reproducibility is the ability to obtain consistent results from scientific work, using the same data, code, and analysis; it differs from replicability, which uses new data.
Reproducibility Project: Psychology
The Reproducibility Project: Psychology was a 2015 Open Science Collaboration effort that replicated 100 psychology studies, finding only 36% produced significant results, a landmark of the open-science movement.
Reproducible Builds
Reproducible builds are a software assurance property where identical source code, build environment, and instructions yield bit-for-bit identical binaries, letting independent parties detect compromised build pipelines.
Reproducing kernel Hilbert space
A reproducing kernel Hilbert space (RKHS) is a Hilbert space of functions in which evaluation at any point is continuous, a condition equivalent to a reproducing kernel existing.
Reproducing kernel method
The reproducing kernel method (RKM) is a numerical technique that solves differential and integral equations by representing the solution as a series in a reproducing kernel Hilbert space.