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Showing 1–19 of 19 reference entries
Describe a quantity as a numerical value with a unit, and distinguish its physical kind from its dimension. Build length, area, volume and rate units, check meaningful combinations, and separate exact unit relations from measurement uncertainty.
DefinitionMathematics & logic · Physics · MeasurementUnit conversionsConvert quantities with exact unit ratios, track cancellation through compound units, and apply the correct powers to area and volume. Distinguish temperature readings from differences, check dimensions and context, and retain measurement uncertainty when reporting.
MethodMathematics & logic · Physics · MeasurementEstimation and uncertaintyDistinguish exact model values, rounded approximations and estimates from measurements. Declare the rounding rule, preserve information through calculations and unit changes, and interpret resolution, precision, accuracy and the stated uncertainty type without turning a report’s digits into guaranteed bounds.
DefinitionMathematics & logic · PhysicsApproximationsBuild a useful estimate, compare a correction with a stated reference scale, and check what is lost when you leave out a term.
ApproximationMathematics & logic · PhysicsSymmetry and invarianceSpecify a transformation, identify what stays unchanged, and distinguish symmetry of an object from invariance of a physical model.
Mathematical statementInformation · Mathematics & logicBits and unsigned binary encodingA bit has two possible states; a fixed-width unsigned binary word encodes an integer.
DefinitionInformation · Mathematics & logicShannon entropy of a discrete distributionShannon entropy measures uncertainty in a specified probability distribution.
DefinitionInformation · Mathematics & logicUndecidability of the halting problemNo total algorithm decides halting for every program and input in a general computation model.
Mathematical statementInformation · Mathematics & logicAsymptotic upper bounds and big OBig O bounds eventual growth up to a fixed constant factor.
DefinitionMeasurement · Mathematics & logicFirst-order uncertainty propagationCombine input uncertainty through a measurement model.
MethodMeasurement · Physics · Mathematics & logicDimensional consistencyUse dimensions to detect impossible quantity equations.
MethodPhysics · Mathematics & logicInvariant spacetime intervalLorentz transformations preserve a combined space-time separation.
ModelPhysics · Mathematics & logicEuler–Lagrange equationsStationary action supplies coordinate equations of motion.
Mathematical statementPhysics · Mathematics & logicHamilton's canonical equationsCanonical coordinates and momenta evolve from the Hamiltonian.
Mathematical statementPhysics · Mathematics & logicWave superposition and interferenceLinear disturbances add; their relative phase determines reinforcement.
ModelPhysics · Mathematics & logicGeodesic motionFree test motion follows the metric connection.
ModelMeasurement · Mathematics & logicCovariance in uncertainty modelsShared input variation belongs in the joint uncertainty description.
MethodPhysics · Mathematics & logicFixed points and local dynamical stabilityFor an autonomous smooth system ẋ=f(x), equilibria satisfy f(x*)=0 and nearby perturbations obey δẋ≈Jδx, J_ij=∂f_i/∂x_j at x*.
Mathematical statementPhysics · Mathematics & logicElementary equilibrium bifurcation modelsA bifurcation is a qualitative change in a parameterized dynamical system.
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