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Showing 91–120 of 360 reference entries

Mathematics & logicPermutation inference under exchangeability

Distribution-free procedures still require assumptions.

Method
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
Mathematics & logicIntermediate values and compact-domain extrema

A continuous real function on a closed bounded interval attains a maximum and minimum and takes every value between its endpoint values.

Mathematical statement
Mathematics & logicProduct, quotient and chain rules

Differentiable real functions satisfy (fg)′=f′g+fg′ and (g∘f)′=(g′∘f)f′.

Mathematical statement
Mathematics & logicMean value theorem

If f is continuous on [a,b] and differentiable on (a,b), a<b, some c∈(a,b) satisfies f′(c)=(f(b)−f(a))/(b−a).

Mathematical statement
Mathematics & logicDarboux intermediate-value property of derivatives

For f differentiable throughout an open real interval, its derivative takes every value strictly between f′(a) and f′(b) at some c∈(a,b), whenever a<b are points of that interval.

Mathematical statement
Mathematics & logicSubstitution in a definite integral

For g of class C¹ on [a,b] and f continuous on an interval containing g([a,b]), ∫ₐᵇ f(g(x))g′(x)dx=∫g(a)ᵍ(b)f(u)du.

Method
Mathematics & logicIntegration by parts

For u,v of class C¹ on [a,b], ∫ₐᵇuv′dx=[uv]ₐᵇ−∫ₐᵇu′v dx.

Method
Mathematics & logicDarboux sums and Riemann integrability

For bounded real f on [a,b], lower and upper Darboux sums use each subinterval's infimum and supremum.

Mathematical statement
Mathematics & logicContinuity and the Riemann integrability criterion

A bounded real function on [a,b] is Riemann integrable exactly when its discontinuity set has Lebesgue measure zero.

Mathematical statement
Mathematics & logicWeierstrass M-test

If real functions fₙ on one set A satisfy |fₙ(x)|≤Mₙ for all x∈A, with Mₙ≥0 and ΣMₙ<∞, then Σfₙ converges uniformly and absolutely on A.

Mathematical statement
Mathematics & logicImproper integrals and independent endpoint limits

An improper integral is the finite limit of proper integrals as a singular endpoint or an infinite endpoint is approached.

Definition
Mathematics & logicIntegral test and p-series

For positive continuous decreasing f on [1,∞), Σₙ₌₁∞f(n) and ∫₁∞f(x)dx converge or diverge together.

Mathematical statement
Mathematics & logicAlternating-series convergence and remainder

If bₙ≥0 decreases to zero, Σ(−1)ⁿbₙ converges; the absolute error after N terms is at most the next omitted magnitude b_(N+1).

Mathematical statement
Mathematics & logicMonotone convergence and Fatou's lemma

For increasing nonnegative measurable fₙ→f, ∫fₙdμ→∫f dμ.

Mathematical statement
Mathematics & logicDominated convergence theorem

If measurable real fₙ→f pointwise and |fₙ|≤g for one integrable g, then ∫fₙdμ→∫f dμ.

Mathematical statement
Mathematics & logicSubgroups and the subgroup test

A subgroup H⊆G is a group under G's restricted operation.

Definition
Mathematics & logicCosets and subgroup index

Left cosets gH={gh:h∈H} partition G.

Definition
Mathematics & logicNormal subgroups and quotient groups

A subgroup N is normal when gNg⁻¹=N for every g∈G.

Mathematical statement
Mathematics & logicIdeals and quotient rings

A two-sided ideal I of R is an additive subgroup absorbing multiplication by R on either side.

Definition
Mathematics & logicHolomorphic functions and Cauchy–Riemann equations

A function is holomorphic on an open set when it is complex differentiable at every point.

Definition
Mathematics & logicComplex contour integration and Cauchy's theorem

For a piecewise C¹ path γ, ∫γf(z)dz=∫f(γ(t))γ′(t)dt.

Mathematical statement
Mathematics & logicCauchy integral formula and derivatives

If f is holomorphic on a neighborhood of a closed disk and z lies inside its positively oriented boundary γ, f⁽ⁿ⁾(z)=n!/(2πi)∮γ f(w)/(w−z)ⁿ⁺¹dw for n≥0.

Mathematical statement
Mathematics & logicComplex Taylor and Laurent expansions

A holomorphic function has a convergent Taylor expansion within a disk free of singularities.

Mathematical statement
Mathematics & logicResidues and the residue theorem

The residue at an isolated singularity is the (z−a)⁻¹ coefficient of its Laurent series.

Mathematical statement
Mathematics & logicFloating-point numbers and roundoff

Floating-point numbers use a sign, finite significand and exponent.

Approximation