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For a suitable twice differentiable function $u$ and an integrable stopping time $T$,

It is the Dynkin's formula with the Brownian motion generator $\frac{1}{2}\Delta$.

A body-centered cubic lattice consists of the points of a cubic lattice together with their body centers. Its reciprocal lattice is face-centered cubic.

The reciprocal lattice isIf $\Omega =a_1\cdot (a_2\times a_3)$, its primitive vectors areand satisfy $a_i\cdot b_j=2\pi {\delta }_{ij}$.

A lattice point is a vector $l=n_1{a}_1+n_2{a}_2+n_3{a}_3$ whose coefficients in a chosen primitive basis are integers.

For $u=\log |\varphi {|}^2$ and zeros of multiplicities $N_r$ at $z_r$, the Taubes equation is

This is the Bruhat decomposition associated with a BN-pair. The Bruhat decomposition is the disjoint unionassociated with a BN-pair.

The queue length in an $M/M/1$ queue is a birth-death process with constant arrival rate $\lambda$ and service rate $\mu$ while nonempty.

For constant birth rate $\lambda$ and death rate $\delta$ away from zero, the chain is transient when $\lambda >\delta$, null recurrent when $\lambda =\delta$, and positive recurrent when $\lambda <\delta$.

For unit jumps with birth and death rates $b(x),d(x)$, the Fokker--Planck drift and diffusion in the conventionare $u=b-d$ and $D=(b+d)/2$.

Approximating the population law by a Poisson law replaces its first two factorial moments by $\lambda$ and ${\lambda }^2$, closing a quadratic first-moment equation as a Riccati equation for $\lambda$.

For birth rates $b_n$, death rates $d_n$, and state probabilities $P_n$,

For birth rates $b_i$ and death rates $d_i$, a reversible measure satisfiesThus ${\pi }_{i+1}/{\pi }_i=b_i/d_{i+1}$, and it is an invariant distribution when the resulting measure is summable and the chain is nonexplosive.

For individual birth and death rates $\lambda ,\mu$ and one initial individual, the finite-time extinction probability satisfiesWhen $\lambda \ne \mu$,

The Yule process is the pure birth process with rate $n\lambda$ in population state $n$. Starting from one individual, it is nonexplosive because the independent holding times have divergent total almost surely.

On a finite measure space, the convergence in the Birkhoff ergodic theorem also holds in $L^1$. Prove it first for bounded truncations by the dominated convergence theorem, then use the $L^1$ contraction $\Vert A_{n}h{\Vert }_1\le \Vert h{\Vert }_1$ and Fatou lemma to remove the truncation.

The surface shear stress isThe torque exerted by the fluid on the disk per unit axial length is therefore

Let a discrete-time chain move up with probability $q$ and down with probability $p=1-q$ away from zero, while at zero it moves up with probability $q$ and stays with probability $p$. It is transient for $q>p$, null recurrent for $q=p$, and positive recurrent for $q<p$. In the positive-recurrent case its invariant distribution isand aperiodicity from the self-loop at zero implies convergence to this distribution.

For $s,t>0$, put $r=s+t$ and $u=t/(s+t)$. Then $(s,t)=(r(1-u),ru)$ and $dsdt=rdrdu$, separating radial gamma and ratio beta integrals.

At an interior maximum-likelihood fit of a logistic-regression model containing an intercept, the intercept score function isConsequently the sum of the fitted probabilities equals the number of observed successes exactly.

For $m=\mathbb{E}N$ and $v=\mathrm{var}N$, the Markov jump-process generator applied to $n$ and $n^2$ givesConsequently