42,772 articles
Decidability of first-order theories
Decidability of first-order theories asks which first-order theories have an algorithm deciding whether any sentence follows from them; Presburger arithmetic is decidable, first-order validity is not.
DECIGO
DECIGO (Deci-hertz Interferometer Gravitational wave Observatory) is a proposed Japanese space-based gravitational-wave detector covering 0.1 to 10 Hz, proposed in 2001 and developed around JAXA.
Decimal
The decimal, or base-10, numeral system is the everyday number system whose digits 0 through 9 take place values in powers of ten, separated by a decimal point.
Decimal time
Decimal time divides the day into powers of ten instead of 24 hours, notably in France from 1793 to 1795 and as Swatch Internet Time in 1998.
Decision curve analysis
Decision curve analysis is a statistical method for evaluating clinical prediction models by their net benefit across threshold probabilities, introduced by Andrew Vickers and Elena Elkin in 2006.
Decision problem
Decision problem: yes/no computational task over inputs (Entscheidungsproblem, German for decision problem). Central to computability and complexity theory; halting problem and first-order validity are undecidable (Church, Turing 1936).
Decision problems for formal languages
Decision problems for formal languages ask whether emptiness, membership, and equivalence are decidable: all are decidable for regular languages, but equivalence and inclusion are undecidable for context-free grammars.
Decision threshold
A decision threshold is a measurement value above which a physical effect, such as low-level radioactivity, is declared present, defined in the ISO 11929 standards.
Declination
Declination, also called the declination angle, is the celestial equivalent of latitude, measuring an object's angular distance north or south of the celestial equator, from 0° to ±90°.
Declustering (statistics)
Declustering is a family of spatial statistics methods that reweight or subsample clustered data so estimates are less biased by preferential sampling, where some areas are oversampled.
Decoction (extraction)
Decoction is a method of extracting water-soluble, heat-stable constituents from plant material by boiling it in water, suited to tough roots, barks, and seeds and dominant in traditional Chinese medicine.
Decoding problem (quantum error correction)
The decoding problem in quantum error correction is the task of inferring a likely error pattern from noisy syndrome measurements and applying a correction so the encoded logical information survives.
Decoherence and robustness of adiabatic quantum computation
Decoherence and robustness of adiabatic quantum computation is the study of how decoherence, thermal noise, and Landau–Zener transitions affect adiabatic quantum computation, whose robustness depends on the annealing scheme.
Decoherence in condensed-matter and mesoscopic systems
Decoherence in condensed-matter and mesoscopic systems is the loss of quantum phase coherence of electrons, spins, or qubit variables in solids, caused by material-inherent baths like phonons and nuclear spins.
Decoherence in spin baths
Decoherence in spin baths is the loss of quantum coherence of a central qubit or spin caused by coupling to an environment of localized spins, described by the central-spin model.
Decoherence rates and timescales
Decoherence rates and timescales measure how quickly quantum superpositions lose coherence through environmental interaction, with timescales that scale with mass and separation and can be vastly shorter than relaxation times.
Decoherence-free subspace
A decoherence-free subspace (DFS) is a subspace of a quantum system's Hilbert space in which states evolve unitarily, providing passive error avoidance when noise is symmetric.
Décollement
Décollement, French for "ungluing," is a fault surface parallel to weak bedding that separates deformed rocks above from rocks below, typical of thrust regions like the Alps.
Decomposition theorem
The decomposition theorem is a 1981 result in algebraic geometry, proved by Beilinson, Bernstein, Deligne, and Gabber, stating that derived direct images of intersection cohomology complexes split into direct sums.
Decoupling (cosmology)
In cosmology, decoupling is the moment a particle species stops interacting thermally with the rest of the universe: neutrinos about 1 second after the Big Bang, photons at recombination.
Decoy-state method
The decoy-state method is a quantum key distribution technique in which a transmitter randomly varies pulse intensities, letting parties estimate single-photon yields and counter photon-number-splitting attacks; it was proposed by Won-Young Hwang in 2002.
Decoy-state quantum key distribution
Decoy-state quantum key distribution is a quantum cryptography technique in which Alice transmits signals at randomly chosen intensity levels to defeat photon number splitting attacks.
Dedekind cut
A Dedekind cut, also called a Dedekind section, is a partition of the rational numbers into two sets marking a real number, devised by Richard Dedekind in 1858.
Dedekind domain
A Dedekind domain, also called a Dedekind ring, is a Noetherian, integrally closed ring, named for Richard Dedekind, in which every nonzero ideal factors uniquely into prime ideals.
Dedekind zeta function
The Dedekind zeta function ζK(s) of a number field K is the analytic function summed over its integral ideals, generalizing the Riemann zeta function, the case K = Q.
Dedoose
Dedoose is a cloud-based application for managing, coding, analyzing, and visualizing qualitative and mixed methods research data, developed by UCLA researchers and known for real-time collaborative team coding.
Deduction theorem
The deduction theorem is a metatheorem of logic stating that if ψ is derivable from Γ plus assumption φ, then φ → ψ is derivable from Γ alone.
Deductive-nomological model
The deductive-nomological model, also known as the DN or covering-law model, is a 1948 account of scientific explanation by Carl G. Hempel and Paul Oppenheim.
Deep Argo
Deep Argo is an expansion of the international Argo program in which profiling floats measure temperature and salinity from the ocean surface to the sea floor every 10 days.
Deep Basin, Alberta
The Deep Basin is a large tight gas region in western Alberta along the foothills, holding natural gas in low-permeability Cretaceous rocks over a broad continuous area.