Consider normalized initial concentration $a$ above $z_m=4H/5$ and $b=a/2$ below it, with $0<a<1$, in the quadratic hindered-settling flux model. The final packed height is $h_c=3aH/5$. The last surviving characteristic of a settling fan lies inside the fan only ifThe upper inequality gives $a\ge a_{\ast }=1-\sqrt{2/3}$; the lower gives $a\le 2/3$. Thus both front curves can be used through the final meeting only for $a_{\ast }\le a\le 2/3$.

If $a<a_{\ast }$, the deposition front leaves the fan through its upper edge before meeting the clearing front. It then travels through uniform concentration $a$ at speed $u_{s}a$; the clearing front stays straight. If $a>2/3$, the clearing front instead leaves the lower edge first, while the deposition front stays at speed $u_{s}b$. Matching the appropriate straight and curved pieces givesThe expressions agree at the transition values. The bounds prevent an algebraic intersection of extrapolated curves from being mistaken for a physical meeting inside the settling rarefaction fan.

A Caccioppoli partition is a countable measurable partition, up to null sets, into sets of finite perimeter with finite sum of relative perimeters. Its interior interfaces are counted twice by that sum. It represents regions of a piecewise constant image signal in the piecewise-constant Mumford–Shah problem.

The planar cluster-count identity rewrites $o(\omega )+2k(\omega )$ as $|V|-1+k(\omega )+k({\bar{\omega }}^{\ast })$. At the self-dual parameter of the random-cluster model, $p/(1-p)=\sqrt{q}$, so its weight is $(\sqrt{q}{)}^{o(\omega )+2k(\omega )}$ up to a configuration-independent factor. Absorbing $(\sqrt{q}{)}^{|V|-1}$ into normalization proves the symmetric weight, with the unbounded dual face counted.

Put $L=\sqrt{D}$, $h(t)={\prod }_{p\mid t}(g(p{)}^{-1}-1)$ and $y_t={\sum }_{\begin{array}{c}m\le L\\ t\mid m\end{array}}g(m){\rho }_m$, where $g$ is a multiplicative arithmetic function supported on squarefree integers. For squarefree integers $m,n$,Thus the quadratic form is $\Sigma ={\sum }_{t\le L}h(t)y_t^2$. Möbius inversion gives $g(d){\rho }_d={\sum }_{d\mid t\le L}\mu (t/d)y_t$. On the permitted squarefree integers, the constraint ${\rho }_1=1$ becomes ${\sum }_t\mu (t)y_t=1$. The Cauchy-Schwarz inequality yields $\Sigma \ge 1/J$, where $J={\sum }_{t}1/h(t)$ over those integers; equality holds at $y_t=\mu (t)/(Jh(t))$.

Changing planetary masses or other system parameters move the frequencies of secular eigenmodes. A particle can cross a secular resonance when its free precession frequency meets a forcing frequency. Passage can change its free eccentricity and mix modes; a single scalar phase replacement generally cannot describe the response.

If both precession and forcing in $\dot{z}=ig(t)(z-z_f)$ share a common mass factor while $z_f$ stays fixed, then $z=z_f+(z(0)-z_f)\exp (i{\int }_0^{t}g(t\prime )dt\prime )$. The Argand diagram circle is unchanged; only its traversal speed varies. With $g(t)=g_{f}t/t_p$, the phase is $g_f{t}^2/(2t_p)$.

For a real two-planet Laplace-Lagrange secular matrix with negative off-diagonal entries, the upper secular eigenmode has anti-aligned apsides and the lower has aligned apsides. Their positive planet-1 to planet-2 amplitude ratios obey $r_p{r}_m=A_{12}/A_{21}$. Under the conventional angular momentum deficit normalization this is $L_2/L_1$.

For $u^{\prime \prime }+[1+k{ϵ}^2+ϵ\cos t]u=0$, set $t=2s$. The Mathieu equation has $a=4+4k{ϵ}^2$ and $q=-2ϵ$. Near the value $4$, the orthonormal even Fourier series basis $1,\cos 2s,\cos 4s,\cos 6s$ gives diagonal entries $0,4,16,36$ and adjacent couplings $\sqrt{2}q,q,q$. The odd basis $\sin 2s,\sin 4s,\sin 6s$ gives diagonal entries $4,16,36$ and adjacent couplings $q,q$. Higher modes require at least six coupling steps to affect the root near $4$, so these truncations determine its coefficients through $q^4$.

Substituting $a=4+c_2{q}^2+c_4{q}^4$ into the two characteristic polynomials and equating coefficients yieldsConverting back gives the displayed gap edges with remainders $O({ϵ}^4)$ in $k$. In a fixed bounded neighborhood of this parametric resonance, the true unstable gap is $k_{-}<k<k_{+}$. The leading slow-amplitude calculation cannot decide exact stability at $k=-1/12$ or $5/12$; the fourth-order shifts put those fixed values just outside the gap for sufficiently small positive $ϵ$. This does not provide a bound uniform in $ϵ$ for their transient amplification.

The diffusion coefficient obtained from a scale transform for an additive-noise diffusion need only be defined on an open interval. If it is Lipschitz, its limit at a finite endpoint is zero: a positive limit would bound the derivative $1/h$ of the inverse scale and prevent the inverse from diverging. Extending it by zero beyond finite endpoints therefore preserves global Lipschitz continuity.

The zero extension of a scale diffusion coefficient at finite endpoints makes the transformed equation globally Lipschitz. Inverting its solution gives the original additive-noise equation. The pathwise bound $|X_t|\le |x|+{\sup }_{s\le T}|W_s|+\Vert b{\Vert }_{\infty }T$ prevents the inverse scale from reaching infinity at any finite time. This proves global strong existence and pathwise uniqueness even when the original drift is not Lipschitz.

The uncentered empirical second-moment matrix averages the outer products of the observations. Its expected value is $\mathrm{Cov}(X)+\mathbb{E}[X]\mathbb{E}[X{]}^{\top }$. It is an unbiased estimator of the covariance matrix when the population expected value is known to be zero. It differs from a sample covariance matrix centered at the sample mean.

A Nambu–Goto action solution with $X^0=t$ is $\mathbf{X}=L\sin (\sigma /L)(\cos (t/L),\sin (t/L))$, for $0\le \sigma \le \pi L/2$. It solves the wave equation, has a fixed endpoint at the origin, and obeys the free-end string boundary condition at the other end. Its proper length is $L$ and its free endpoint has angular speed $1/L$ and spatial speed one.

In units $\hslash =1$, periodic-angle quantization gives canonical charge $Q_{\theta }=\ell \in \mathbb{Z}$. The mechanical charge is $Q_0=\ell +\theta T/(2\pi )$ and the rotating-kink mass gives the displayed leading semiclassical spectrum. The $T=1$ and $T=-1$ families are related by reversing the kink. Theta periodicity relabels the integer; fluctuation corrections are not excluded by this leading calculation.

For a complex semisimple Lie algebra, restrict the module $\mathfrak{h}\oplus {⨁}_{j\ne 0}{\mathfrak{g}}_{j\alpha }$ to the sl2 subalgebra associated with a root. All its weights are even. Its raising operator maps the weight-zero space $\mathfrak{h}$ onto the one-dimensional line of the chosen root vector, so there is exactly one nontrivial irreducible summand: the adjoint module of highest weight $2$. Thus the root spaces at $\pm \alpha$ are one-dimensional and $2\alpha$ is not a root. For any parallel root $c\alpha$, the integers $2c$ and $2/c$ have product $4$; excluding double and half roots leaves only $c=\pm 1$.

Every right-invariant Riemannian metric on the Heisenberg group has Killing vector fields ${\partial }_x$, ${\partial }_y+x{\partial }_z$ and ${\partial }_z$. Their Lie brackets of vector fields reproduce $[X,Y]=Z$ and the central relations. Their flows are right translations. The dual frame of the right-invariant coframe is different and has the opposite Lie-bracket sign.

Let ${\Sigma }_{d0}$ be the uniform background dust surface density of a disk and ${\delta }_d=({\Sigma }_d-{\Sigma }_{d0})/{\Sigma }_{d0}$ its fractional perturbation. Here $k$ is the radial wavenumber, $\Omega$ is the epicyclic frequency and $u$ is a real velocity amplitude. For that uniform background and late velocity $v_x=u\cos (kx-\Omega t)$, linear dust continuity equation gives ${\partial }_t{\delta }_d=-{\partial }_x{v}_x=ku\sin (kx-\Omega t)$. Integrating yields the displayed formula. The coherent travelling-wave fractional excess is $|ku|/\Omega$, with validity requiring this number much smaller than one. The static term $C(x)$ records initial density and transient displacement: drag damps velocity, but supplies no density diffusion. The long-wavelength gas wave has the same fractional density amplitude, so entrainment alone does not produce an additional dust-to-gas ratio enhancement at this order.

Fitting a mixture model to regression residuals treats the fitted mean adjustment as fixed. Even with independent homoscedastic errors, ordinary least-squares residuals have covariance matrix ${\sigma }^2(I-H)$ and satisfy fitted linear constraints, so they are not exactly independent observations. A joint mixture regression with shared slopes or a bootstrap of the whole fitting process better accounts for the first-stage estimation uncertainty.

If $H:{\mathcal{A}}^{\mathrm{op}}\times \mathcal{B}\to \mathbf{Set}$ has chosen representations ${\psi }_B:\mathcal{A}(-,GB)\cong H(-,B)$, the Yoneda lemma determines a unique functor $G$ on morphisms by $\mathcal{A}(-,Gb)={\psi }_{B^{\prime }}^{-1}H(-,b){\psi }_B$. This makes the representing natural isomorphisms natural in $B$.

The independent constraints $|{\phi }_0|\le 1$ and $|\phi |\le 1$ separate the dual supremum into $|\Omega |+|Du|(\Omega )$. They do not define square-root graph area. For $|\nabla u|=1$ the box-constrained value is $2|\Omega |$, while the relaxed graph-area functional is $\sqrt{2}|\Omega |$.

For an assumed $W^{1,1}$ minimizer of $\alpha A(u)+\frac{1}{2}\Vert u-g{\Vert }_2^2$, compactly supported variations give $u-g-\alpha \mathrm{div}(\nabla u/\sqrt{1+|\nabla u{|}^2})=0$ in distributions. If the regularizer is instead the total variation seminorm, a bounded calibration field replaces the quotient and handles zero gradients.