A degree-$d$ rational map has total critical multiplicity $2d-2$. Here is an algebraic proof. Critical points are isolated zeros of local derivatives and are finite in number by compactness. Change domain and range Möbius coordinates so that the poles are $d$ simple finite poles and infinity is a regular point with a finite image. Write $R=P/Q$, with $\mathrm{deg}Q=d$, and $R(z)=a+b/z+O(z^{-2})$, $b\ne 0$. Then $W=P^{\prime }Q-P{Q}^{\prime }$ has degree exactly $2d-2$, since $R^{\prime }=W/Q^2\sim -b/z^2$. At a pole, $W=-P{Q}^{\prime }\ne 0$. Thus the roots of $W$ are precisely the critical points and their zero orders are the critical multiplicities. The fundamental theorem of algebra gives the count; the coordinate changes preserve it.

An object of a site is J-irreducible when its only covering sieve on a category is the maximal sieve. In particular the empty sieve cannot cover it. Every arrow from a J-irreducible object belongs to any covering sieve on its codomain: the pulled-back sieve must contain the identity. This makes the induced topology on the full subcategory of J-irreducible objects trivial.

A coverage on a category is rigid when each object is covered by the sieve generated by arrows from J-irreducible objects of a site. Restriction to their full subcategory identifies the sheaves on a site with its presheaf category. A presheaf on that subcategory extends by the right Kan extension $C\mapsto \mathrm{Nat}(yC{|}_{\mathcal{D}},F)$: every covering sieve restricts to the full representable on $\mathcal{D}$, which proves the sheaf condition directly.

Under the inequality in one-sided bounds for adjoining a positive element, if $a\ge 1$ belongs to the cover of a value in a lattice-ordered group $V^{\ast }$ but not to $V$, then $⟨V,a{⟩}_c=V^{\ast }$. Thus every $b\ge 1$ in the cover is bounded above by both $v{a}^n$ and $a^{m}w$ for suitable nonnegative $v,w\in V$ and integers $m,n\ge 0$. The corresponding right and left coset bounds give the displayed cofinality, without first assuming that $V$ is normal. Left-coset order is obtained by inversion of right-coset order.

With real complete polarization vectors, the covariant photon Fock space oscillator commutators and ${\sum }_{\lambda ,{\lambda }^{\prime }}{ϵ}_{\mu }^{\lambda }{ϵ}^{\nu {\lambda }^{\prime }}{\eta }_{\lambda {\lambda }^{\prime }}={\delta }_{\mu }{}^{\nu }$ imply the equal-time canonical commutation relations $[A_{\mu }(\mathbf{x}),-{\dot{A}}^{\nu }(\mathbf{y})]=i{\delta }_{\mu }{}^{\nu }{\delta }^3(\mathbf{x}-\mathbf{y})$. The two mixed creation-annihilation terms add; the two coordinate-coordinate or momentum-momentum terms cancel after their polarization sums. The sign of the time-component oscillator is essential to the identity. Boundary-induced canonical transformation in Feynman gauge explains the momenta for the unsubtracted density.

The symmetric Alexander polynomial normalized by the Conway polynomial is uniquely fixed for a knot. Its sign matters in the signed Jones evaluation at minus one, whereas the knot determinant retains only the absolute value.

Introduce a Boolean variable for each gate output and impose its equivalence to the gate's input function with a constant number of clauses. A final unit clause forces acceptance. For a bounded-fan-in Boolean circuit, the formula size is linear in the gate count and it is satisfiable exactly when some input makes the Boolean circuit output one. Auxiliary variables extend the satisfying assignments; this is equisatisfiability, not equality as functions of the enlarged variable set.

If two positive bumps of an order automorphism move a point $c$ beyond an interval $[c,d]$, their conjugacy can be chosen to fix that interval: begin with the identity there, complete the increasing map between fundamental intervals, and extend equivariantly along bump iterates. If both bump supports lie in one fundamental interval of another positive motion $h$, fix that cell's endpoints and repeat the conjugator on all its $h$-translates. The result commutes with $h$, and with any automorphism supported in the interval fixed pointwise.

There is no positive integer right triangle whose area is a square. For a hypothetical primitive triangle of minimal hypotenuse, its primitive Pythagorean parametrization makes $m,n,m-n,m+n$ pairwise coprime squares. Write $m=r^2$, $n=s^2$, $m+n=u^2$, $m-n=v^2$. Modulo eight forces $m$ odd and $n$ even. The new integer legs $(u+v)/2,(u-v)/2$ have hypotenuse $r$ and area $(s/2{)}^2$, a smaller positive hypotenuse, contradicting infinite descent. Clearing denominators extends the conclusion to rational right triangles of area one.

A primitive Pythagorean triple of area twice a square would satisfy $mn(m-n)(m+n)=2s^2$. Pairwise coprimality makes the odd factors squares and the even factor twice a square. The possibility $m$ even is excluded modulo eight. Thus $m=a^2,n=2b^2,m+n=c^2,m-n=d^2$. The coprime integers $u=(c+d)/2,v=(c-d)/2$ have $uv=b^2$, hence are themselves squares, and $a^2=u^2+v^2$ contradicts fourth-power sum cannot be a square. Clearing denominators gives the assertion for rational triangles.

The orthogonal complements of the universal frames define a complex vector bundle of rank $n-k$ inside the trivial ${\mathbb{C}}^n$ bundle. The orthogonal projector $I-{\sum }_i{v}_i{v}_i^{\ast }$ is smooth of constant rank, giving local bundle frames. Its underlying real bundle has canonical orientation and rank $2(n-k)$. Its sphere bundle is exactly $V_{k+1}({\mathbb{C}}^n)$, by appending the unit vector in the complement to the frame.

Use the complement bundle on a complex Stiefel manifold inductively. If the ring for $V_k$ is exterior with smallest positive degree $2n-2k+1$, the complement bundle has Euler degree $2(n-k)$, in which base cohomology vanishes. Its Euler class is consequently zero. The Gysin ring splitting for an odd-dimensional sphere bundle adds one exterior generator of degree $2(n-k)-1$. The initial base $V_0$ is a point. This gives the full integral cohomology ring and in particular its torsion-freeness. At $k=n$, the unitary group has Poincare polynomial ${\prod }_{j=0}^{n-1}(1+t^{2j+1})$.

Lift finite homogeneous generators of the associated graded module of a right ideal $I$ to $x_i\in I$ of degrees $d_i$. Successive leading-symbol cancellations write an element $x\in F_{d}I$ as finite partial sums ${\sum }_i{x}_i{a}_i^{(q)}$ with residual in $F_{d-q}R$. The coefficient increments lie in $F_{d-q-d_i}R$ and therefore converge in the complete negative filtration. Multiplication is continuous, so their limits express $x$ as a finite sum ${\sum }_i{x}_i{a}_i$. This generates the actual right ideal and does not presuppose that it is closed. The left-sided statement is analogous.

A freely falling particle's physical momentum is measured in the local orthonormal frame of a comoving observer. With proper peculiar velocity $\mathbf{v}=ad\mathbf{x}/dt$ and Lorentz factor $\gamma =(1-v^2{)}^{-1/2}$, it is $m\gamma \mathbf{v}$. It differs by one factor of the scale factor from the conserved comoving momentum. For a nonrelativistic particle, its peculiar velocity therefore decays as $a^{-1}$.

The $k$th logarithmic derivative in the additive formal logarithm coordinate defines the Coates–Wiles homomorphism. Products of local units become sums under this map. For elliptic units, differentiating the underlying complex elliptic function expresses the result in terms of critical Hecke L-function values divided by a CM period.

Assume $K_{\mathfrak{p}}={\mathbb{Q}}_p$, $p>2$, $f(t)\in {\mathbb{Z}}_p[[t]{]}^{\times }$, and $[\pi ]t\equiv t^p(\mathrm{mod}p)$. Then the displayed ratio lies in $1+p{\mathbb{Z}}_p[[t]]$, so its logarithm divided by $p$ is integral. A formal-group isomorphism over the completed unramified coefficient ring transfers it to an integral Amice transform. A norm relation makes the corresponding p-adic measure supported on units. Its $k$th moment has the Euler correction $1-{\pi }^k/p$.

For odd $p$, the Coleman norm operator satisfies the displayed inclusion for every $k\ge 1$. Write $M_h$ for multiplication by $h$ on the finite free module $R$ over $\varphi (R)$. Its trace is $p\varphi (S(h))$, where $S$ is the Coleman trace operator. In $\det (I+p^k{M}_h)$ the linear term is therefore divisible by $p^{k+1}$, and all higher terms are divisible by $p^{2k}$. Congruence reflection for Frobenius substitution gives the assertion. A norm-fixed element of $1+pR$ lies in $1+p^{k}R$ for every $k$ and hence equals $1$.

Every unit $\overline{f}\in {\mathbb{F}}_p[[T]{]}^{\times }$ has a unique Coleman norm operator-fixed lift to ${\mathbb{Z}}_p[[T]{]}^{\times }$. Choose any lift $f$ and use $Nf\equiv f(\mathrm{mod}p)$. The consecutive quotients of the iterates are $N^n(Nf/f)\in 1+p^{n+1}R$ by Coleman norm contraction, so they converge coefficientwise uniformly in the p-adic integers. Their limit is norm-fixed by continuity. Two such lifts have norm-fixed quotient in $1+pR$ and therefore coincide. Uniqueness also makes the lifting map multiplicative and independent of the initial lift.

The Weyl group of the Cn root system is the signed symmetric group. A Weyl reflection in $2{\epsilon }_i$ changes the sign of coordinate $i$; one in ${\epsilon }_i-{\epsilon }_j$ interchanges coordinates $i,j$; one in ${\epsilon }_i+{\epsilon }_j$ interchanges and negates both coordinates. These generate all independent sign changes and all permutations, giving order $2^{n}n!$.

Choose positive roots of a root system ${\epsilon }_i-{\epsilon }_j$, ${\epsilon }_i+{\epsilon }_j$ for $i<j$, and $2{\epsilon }_i$. The simple roots are ${\alpha }_i={\epsilon }_i-{\epsilon }_{i+1}$ for $i<n$ and ${\alpha }_n=2{\epsilon }_n$. Their coroots are ${\alpha }_i^{\vee }={\epsilon }_i-{\epsilon }_{i+1}$ and ${\alpha }_n^{\vee }={\epsilon }_n$. Therefore the fundamental weights and Weyl vector areThe highest root is $2{\epsilon }_1=2{\alpha }_1+\cdots +2{\alpha }_{n-1}+{\alpha }_n$. These formulas include rank one.