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Showing 1–19 of 19 reference entries

Mathematics & logic · Physics · MeasurementQuantities and units

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.

Definition
Mathematics & logic · Physics · MeasurementUnit conversions

Convert 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.

Method
Mathematics & logic · Physics · MeasurementEstimation and uncertainty

Distinguish 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.

Definition
Mathematics & logic · PhysicsApproximations

Build a useful estimate, compare a correction with a stated reference scale, and check what is lost when you leave out a term.

Approximation
Mathematics & logic · PhysicsSymmetry and invariance

Specify a transformation, identify what stays unchanged, and distinguish symmetry of an object from invariance of a physical model.

Mathematical statement
Information · Mathematics & logicBits and unsigned binary encoding

A bit has two possible states; a fixed-width unsigned binary word encodes an integer.

Definition
Information · Mathematics & logicShannon entropy of a discrete distribution

Shannon entropy measures uncertainty in a specified probability distribution.

Definition
Information · Mathematics & logicUndecidability of the halting problem

No total algorithm decides halting for every program and input in a general computation model.

Mathematical statement
Information · Mathematics & logicAsymptotic upper bounds and big O

Big O bounds eventual growth up to a fixed constant factor.

Definition
Measurement · Mathematics & logicFirst-order uncertainty propagation

Combine input uncertainty through a measurement model.

Method
Measurement · Physics · Mathematics & logicDimensional consistency

Use dimensions to detect impossible quantity equations.

Method
Physics · Mathematics & logicInvariant spacetime interval

Lorentz transformations preserve a combined space-time separation.

Model
Physics · Mathematics & logicEuler–Lagrange equations

Stationary action supplies coordinate equations of motion.

Mathematical statement
Physics · Mathematics & logicHamilton's canonical equations

Canonical coordinates and momenta evolve from the Hamiltonian.

Mathematical statement
Physics · Mathematics & logicWave superposition and interference

Linear disturbances add; their relative phase determines reinforcement.

Model
Physics · Mathematics & logicGeodesic motion

Free test motion follows the metric connection.

Model
Measurement · Mathematics & logicCovariance in uncertainty models

Shared input variation belongs in the joint uncertainty description.

Method
Physics · Mathematics & logicFixed points and local dynamical stability

For 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 statement
Physics · Mathematics & logicElementary equilibrium bifurcation models

A bifurcation is a qualitative change in a parameterized dynamical system.

Model