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Family closed under subsets and countable unions
𝜎-ideal, or sigma ideal, of a σ-algebra (𝜎, read "sigma") is a subset with certain desirable closure properties. It is a special type of ideal. Its
Sigma-ideal
North American collegiate fraternity
cultivate and maintain the high ideals of friendship, justice, and learning upon which Sigma Chi was founded." Sigma Chi was founded in 1855 by Benjamin
Sigma_Chi
North American collegiate sorority
associations in the United States and Canada. Phi Sigma Sigma was founded to establish the twin ideals of promoting the brotherhood of man and alleviation
Phi_Sigma_Sigma
Mathematical set regarded as insignificant
also need this ideal to be a sigma-ideal, so that countable unions of negligible sets are also negligible. If I and J are both ideals of subsets of the
Negligible_set
Method for converting signals between digital and analog
Delta–sigma (ΔΣ; or sigma–delta, ΣΔ) modulation is an oversampling method for encoding signals into low bit depth digital signals at a very high sample-frequency
Delta-sigma_modulation
Slang terms for men
Bateman from the 2000 film American Psycho is often cited as an ideal representation of a "sigma male", both through memes and unironic discussion. Beth Skwarecki
Alpha_and_beta_male
American collegiate fraternity
keeping with the ideal of democracy which had always been part of the fraternity's creed. Thus, responsive to this thinking, Sigma Alpha Mu at its 1953
Sigma_Alpha_Mu
Model of electrically conducting fluids
σ n σ q σ u σ {\displaystyle \mathbf {J} =\sum _{\sigma }n_{\sigma }q_{\sigma }\mathbf {u} _{\sigma }} and the center of mass velocity expressed as: v
Magnetohydrodynamics
Ideal of the nilpotent elements
that there is a prime ideal that does not contain f . {\displaystyle f.} Consider the set Σ {\displaystyle \Sigma } of all ideals that do not contain any
Nilradical_of_a_ring
Probability distribution
{\textstyle \sigma ^{2}} is the variance. The standard deviation of the distribution is the positive value σ {\displaystyle \sigma } (sigma). A random
Normal_distribution
International historically Black American collegiate fraternity
Phi Beta Sigma Fraternity, Inc. (ΦΒΣ) is a historically African American fraternity. It was founded at Howard University in Washington, D.C., in 1914
Phi_Beta_Sigma
North American collegiate fraternity
Alpha Sigma Phi (ΑΣΦ), commonly known as A Sig, is an intercollegiate men's social fraternity. Founded in 1845 at Yale University in New Haven, Connecticut
Alpha_Sigma_Phi
American collegiate fraternity
Delta Sigma Phi (ΔΣΦ), commonly known as Delta Sig, is a fraternity established in 1899 at The City College of New York (CCNY). It was likely the first
Delta_Sigma_Phi
International historically African American sorority
Delta Sigma Theta Sorority, Inc. (ΔΣΘ) is a historically African American sorority. The organization was founded by college-educated women dedicated to
Delta_Sigma_Theta
Gives information about the Galois module structure of class groups of cyclotomic fields
\theta (F)=\sum _{\sigma \in G_{F}}a_{\sigma }\sigma \in \mathbb {Z} [G_{F}]} and if J {\displaystyle J} is any fractional ideal of F {\displaystyle
Stickelberger's_theorem
North American collegiate fraternity
Sigma Pi (ΣΠ) is a collegiate fraternity in North America. As of 2021, it had more than 5,000 undergraduate members and over 118,000 alumni. The fraternity
Sigma_Pi
Partially ordered vector space, ordered as a lattice
{\displaystyle \sigma } -ideal, but the converse is not true in general. The intersection of an arbitrary family of bands is again a band. As with ideals, for every
Riesz_space
International collegiate fraternity
"ideal of transcending racial, national, and religious differences." Beta Sigma Rho was founded at Cornell University on October 12, 1910. Beta Sigma Rho
Pi_Lambda_Phi
Ideal gas with no physical scale
The scale-free ideal gas (SFIG) is a physical model assuming a collection of non-interacting elements with a stochastic proportional growth. It is the
Scale-free_ideal_gas
Algebraic concept in measure theory, also referred to as an algebra of sets
from sets to numbers σ-algebra – Algebraic structure of set algebra Sigma-ideal – Family closed under subsets and countable unions 𝜎-ring – Family of
Field_of_sets
Measure of the fluid slip in the impeller of a compressor or a turbine
w 2 ′ V w 2 {\displaystyle \sigma ={\frac {V'_{w2}}{V_{w2}}}} where, V'w2 : Actual Whirl Velocity Component , Vw2 : Ideal Whirl Velocity Component Usually
Slip_factor
Physical law on the emissive power of black body
∘ = σ T 4 . {\displaystyle M^{\circ }=\sigma \,T^{4}.} The constant of proportionality, σ {\displaystyle \sigma } , is called the Stefan–Boltzmann constant
Stefan–Boltzmann_law
Non-tensorial representation of the spin group
{i} &=-\sigma _{2}\sigma _{3}=-i\sigma _{1}\\\mathbf {j} &=-\sigma _{3}\sigma _{1}=-i\sigma _{2}\\\mathbf {k} &=-\sigma _{1}\sigma _{2}=-i\sigma _{3}\end{aligned}}}
Spinor
Foundational principle in quantum physics
that year and by Hermann Weyl in 1928: σ x σ p ≥ ℏ 2 {\displaystyle \sigma _{x}\sigma _{p}\geq {\frac {\hbar }{2}}} where ℏ = h 2 π {\displaystyle \hbar
Uncertainty_principle
Production economics term
Sigma Articles. Lean Sigma Corporation. 5 June 2013. Retrieved 19 September 2013. McShane-Vaughn, Mary (11 January 2023). The ASQ Certified Six Sigma
Rolled_throughput_yield
North American collegiate fraternity
Phi Sigma Kappa (ΦΣΚ), colloquially known as Phi Sig or PSK, is a men's social and academic fraternity with approximately 74 active chapters and provisional
Phi_Sigma_Kappa
Molecular model for describing polymers
An ideal chain (or freely-jointed chain) is the simplest model in polymer chemistry to describe polymers, such as nucleic acids and proteins. It assumes
Ideal_chain
Model of intermolecular interactions
{\displaystyle V_{\text{LJ}}(r)=4\varepsilon \left[\left({\frac {\sigma }{r}}\right)^{12}-\left({\frac {\sigma }{r}}\right)^{6}\right],} where r is the distance between
Lennard-Jones_potential
Puerto Rican social fraternity
Phi Sigma Alpha (ΦΣΑ), commonly known as La Sigma, is a Puerto Rican fraternity originally established as the Sigma Delta Alpha Fraternity (Sociedad de
Phi_Sigma_Alpha
In commutative algebra, the norm of an ideal is a generalization of a norm of an element in the field extension. It is particularly important in number
Ideal_norm
Protagonist from American Psycho
various online communities, some of which portray Bateman as an ideal representation of a "sigma male". At the beginning of American Psycho, Bateman is a 27-year-old
Patrick_Bateman
Collegiate honour society for international studies
society's motto: "Prudence, Ideals, Power". Sigma Iota Rho's symbols are a spider, falcon, and lightning representing prudence, ideals, and power. Its colors
Sigma_Iota_Rho
Formula to quantify column buckling under a given load
− 1 E ( σ y 2 π ) 2 ( l k ) 2 {\displaystyle \sigma _{cr}=\sigma _{y}-{1 \over E}{\left({\frac {\sigma _{y}}{2\pi }}\right)}^{2}{\left({\frac {l}{k}}\right)}^{2}}
Johnson's_parabolic_formula
Ring in which every ideal is principal
right (left) ideal ring is a ring R in which every right (left) ideal is of the form xR (Rx) for some element x of R. (The right and left ideals of this form
Principal_ideal_ring
Value accounting for thermodynamic non-ideality of mixtures
account for deviation of a mixture of chemical substances from ideal behaviour. In an ideal mixture, the microscopic interactions between each pair of chemical
Activity_coefficient
Dimensionless parameter in chemistry
system: σ θ 2 = σ 2 τ 2 = 2 B o + 8 B o 2 {\displaystyle \sigma _{\theta }^{2}={\frac {\sigma ^{2}}{\tau ^{2}}}={\frac {2}{\mathit {Bo}}}+{\frac {8}{{\mathit
Bodenstein_number
American college fraternity (1921–2020)
Sigma Mu Sigma (ΣΜΣ) is a former American college fraternity founded in 1921 at Trine University, formerly Tri-State University. Sigma Mu Sigma was historically
Sigma_Mu_Sigma
Math concept
{\displaystyle \sigma _{1},\sigma _{2}\in {\mathcal {K}}} is a face of both σ 1 {\displaystyle \sigma _{1}} and σ 2 {\displaystyle \sigma _{2}} . Note that
Polyhedral_complex
Entropy production in Newtonian fluids
{\begin{aligned}v_{i}{\partial \sigma _{ij} \over {\partial x_{j}}}&={\partial \over {\partial x_{j}}}\left(\sigma _{ij}v_{i}\right)-\sigma _{ij}{\partial v_{i}
General equation of heat transfer
General_equation_of_heat_transfer
Measure of statistical effect size
{\displaystyle \sigma } ) of samples (s) and controls (c). Given these values ( μ s {\displaystyle \mu _{s}} , σ s {\displaystyle \sigma _{s}} , and μ c
Z-factor
Defunct American collegiate fraternity
Institute in Fort Wayne, Indiana. In May 1965, it was absorbed in part by Alpha Sigma Phi (ΑΣΦ). Alpha Gamma Upsilon was founded by Herbert R. Carter, Homer H
Alpha_Gamma_Upsilon
American collegiate service sorority
same ideals of Gamma Sigma Sigma while also emphasizing inclusive practices. "Gamma Sigma Sigma - 2008 Alumni Press Kit" (PDF). Gamma Sigma Sigma. Becque
Gamma_Sigma_Sigma
Mathematical ring
quotient of a polynomial algebra over a field by a square-free monomial ideal. Such ideals are described more geometrically in terms of finite simplicial complexes
Stanley–Reisner_ring
North American collegiate fraternity
Sigma Tau Gamma (ΣΤΓ), commonly known as Sig Tau, is a United States college social fraternity founded on June 28, 1920, at the University of Central
Sigma_Tau_Gamma
its badge. Its flower was the violet. Became the Gamma Beta Sigma chapter of Alpha Sigma Alpha. Phi Mu Epsilon (ΦΜΕ) music sorority was established on
Defunct North American collegiate sororities
Defunct_North_American_collegiate_sororities
Inclusion of one mathematical structure in another, preserving properties of interest
homomorphism σ : E → F {\displaystyle \sigma :E\rightarrow F} . The kernel of σ {\displaystyle \sigma } is an ideal of E {\displaystyle E} , which cannot
Embedding
Intermolecular forces between oppositely-charged sites on molecules
In chemistry, sigma hole interactions (or σ-hole interactions) are a family of intermolecular forces that can occur between several classes of molecules
Sigma_hole_interactions
American college insurance fraternity
Sigma. Each of the three sides symbolizes three of four fraternal ideals. Gamma Iota Sigma Coat of Arms is in the shape of what is known as a fire mark. Fire
Gamma_Iota_Sigma
North American general sorority
selected based on their representation of the ideals of Beta Sigma Phi. The Torch is the online magazine of Beta Sigma Phi, publishing stories and poems by members
Beta_Sigma_Phi
Algebraic structure
monoid). Any ideal of a ring with the multiplication of the ring. The set of all finite strings over a fixed alphabet Σ {\displaystyle \Sigma } with concatenation
Semigroup
Mathematical object
\mathbb {R} ^{n}} ). The family of ideal lattices for the ring R {\displaystyle R} under the embedding σ {\displaystyle \sigma } is the set of all lattices
Ideal_lattice
American coed college honor fraternity
Bigelow Arthur Kresge John Doak Harold Patterson Harry Hill Phi Sigma Pi's established ideals for its members called the Tripod: scholarship, leadership and
Phi_Sigma_Pi
Algebraic structure used in analysis
{\displaystyle \sigma :A\otimes A\otimes A\to A\otimes A\otimes A} is defined as σ = ( i d ⊗ τ ) ∘ ( τ ⊗ i d ) , {\displaystyle \sigma =(\mathrm {id} \otimes
Lie_algebra
Passive two-terminal electrical component that stores energy in its magnetic field
a short circuit. The constitutive equation describes the behavior of an ideal inductor with inductance L {\displaystyle L} , and without resistance, capacitance
Inductor
Generalization of mass, length, area and volume
statement that the ideal of null sets is κ {\displaystyle \kappa } -complete. A measure space ( X , Σ , μ ) {\displaystyle (X,\Sigma ,\mu )} is called
Measure_(mathematics)
Photographic lens
this lens an ideal partner for APS-C and MFT cameras. An aesthetically updated version, the Sigma 30mm F2.8 DN Art was announced by Sigma on January 29
Sigma_30mm_F2.8_EX_DN
Model for superfluidity and traffic
{v} _{\rm {n}}=-{\frac {\rho _{\rm {n}}}{\rho }}\nabla p-\rho _{\rm {s}}\sigma \nabla T+\eta \nabla ^{2}\mathbf {v} _{\rm {n}};} ρ s ∂ v s ∂ t + ρ s (
Two-fluid_model
Electronic component
)&=j\omega Q(\omega )=j\omega \oint _{\Sigma }{\boldsymbol {D}}({\boldsymbol {r}},\omega )\cdot \mathrm {d} {\boldsymbol {\Sigma }}\\&=\left[G(\omega )+j\omega
Capacitor
Particular kind of algebraic structure
unital Banach algebra A e {\displaystyle A_{e}} so as to form a closed ideal of A e {\displaystyle A_{e}} . Often one assumes a priori that the algebra
Banach_algebra
Relative measure of dispersion expressed as the ratio of standard deviation to the mean
It is defined as the ratio of the standard deviation σ {\displaystyle \sigma } to the mean μ {\displaystyle \mu } (or its absolute value, | μ | {\displaystyle
Coefficient_of_variation
Protein-coding gene in the species Homo sapiens
selectivity and affinity for sigma-2 receptors, and high lipophilicity, making them ideal for usage in the brain. Because sigma-2 receptors are highly expressed
Sigma-2_receptor
Concept in magnetohydrodynamics
\times \mathbf {B} =\mathbf {J} /\sigma } where v {\displaystyle \mathbf {v} } is the velocity field. σ {\displaystyle \sigma } is the electric conductivity
Induction_equation
Measure of a substance's ability to resist or conduct electric current
sigma _{xx}&\sigma _{xy}&\sigma _{xz}\\\sigma _{yx}&\sigma _{yy}&\sigma _{yz}\\\sigma _{zx}&\sigma _{zy}&\sigma
Electrical resistivity and conductivity
Electrical_resistivity_and_conductivity
Gröbner bases for non-commutative algebra
⊆ k ⟨ X ⟩ {\displaystyle \{g_{\sigma }\}_{\sigma \in S}\subseteq k\langle X\rangle } which generates a 2-sided ideal I {\displaystyle I} of k ⟨ X ⟩ {\displaystyle
Bergman's_diamond_lemma
{\displaystyle s_{N}(X_{1},\ldots ,X_{N})=\sum _{\sigma \in S_{N}}\operatorname {sgn}(\sigma )X_{\sigma (1)}\dotsm X_{\sigma (N)}=0~} The m × m matrix ring over any
Polynomial_identity_ring
Skeletonized version of algebraic geometry
constructions such as the Amplituhedron and tropological (topological Carrollian) sigma models. Tropical geometry has also found applications in phylogenetics.
Tropical_geometry
Filipino college confraternity
Delta Sigma Xi, Inc. (ΔΣΞ) (also Delta Sigma Xi) is a confraternity that was established at the Manuel Luis Quezon University (MLQU), Philippines, in 1971
Delta_Sigma_Xi
Concept in astronomy
The M–sigma (or M–σ) relation is an empirical correlation between the stellar velocity dispersion σ of a galaxy bulge and the mass M of the supermassive
M–sigma_relation
Measure of the size of the ring of integers
\left({\begin{array}{cccc}\sigma _{1}(b_{1})&\sigma _{1}(b_{2})&\cdots &\sigma _{1}(b_{n})\\\sigma _{2}(b_{1})&\ddots &&\vdots \\\vdots &&\ddots &\vdots \\\sigma _{n}(b_{1})&\cdots
Discriminant of an algebraic number field
Discriminant_of_an_algebraic_number_field
Video game series
blatantly evil villains like Sigma, the writing staff decided to leave them some "moral leeway". They did not want the ideals of Repliforce and the Maverick
Mega_Man_X
Four-dimensional number system
-i\,\sigma _{1}=-\sigma _{2}\,\sigma _{3},\quad \mathbf {j} \mapsto -i\,\sigma _{2}=-\sigma _{3}\,\sigma _{1},\quad \mathbf {k} \mapsto -i\,\sigma _{3}=-\sigma
Quaternion
Aspect of algebraic number theory
number field K, and the way the prime ideals P of the ring of integers OK factorise as products of prime ideals of OL, provides one of the richest parts
Splitting of prime ideals in Galois extensions
Splitting_of_prime_ideals_in_Galois_extensions
Physics calculation for collisions
two atomic or molecular species in a given volume, per unit time. In an ideal gas, assuming that the species behave like hard spheres, the collision frequency
Collision_frequency
General-purpose programming language
Najaarsconferentie (Dutch UNIX Users Group). even though the design of C is far from ideal, its influence on Python is considerable. "Classes". The Python Tutorial
Python_(programming_language)
Family of sets closed under countable unions
mathematics, a nonempty collection of sets is called a 𝜎-ring (pronounced sigma-ring) if it is closed under countable union and relative complementation
Sigma-ring
American actor (born 1961)
where he studied theater and English. While there, he was a member of the Sigma Chi fraternity and became friends with future vice president Mike Pence
Woody_Harrelson
When an idea extends to a principal ideal in an extension of algebraic number fields
principal ideal of L / K {\displaystyle L/K} , since ( A O L ) σ = A σ O L = A ⋅ H O L = A O L {\displaystyle (A{\mathcal {O}}_{L})^{\sigma }=A^{\sigma }{\mathcal
Principalization_(algebra)
American collegiate Hispanic honor society
membership in support of the Society's goals and ideals. Unlike many collegiate honor societies, Sigma Delta Pi was conceived, planned, and funded entirely
Sigma_Delta_Pi
Chemical compound
and thermal stability. Its high boiling point and stability makes it an ideal candidate for separation processes and high temperature reactions. TEGDME
Tetraethylene glycol dimethyl ether
Tetraethylene_glycol_dimethyl_ether
Geometric placement based on ideal distances
The function σ {\displaystyle \sigma } is a cost or loss function that measures the squared differences between ideal ( m {\displaystyle m} -dimensional)
Stress_majorization
Measure of the error of an estimator
sigma ^{2}+\sigma ^{4}\\&={\frac {(n-1)^{2}}{a^{2}}}\operatorname {E} \left[S_{n-1}^{4}\right]-2\left({\frac {n-1}{a}}\right)\sigma ^{4}+\sigma ^{4}&&\operatorname
Mean_squared_error
\mu _{b}} and standard deviation σ a {\displaystyle \sigma _{a}} and σ b {\displaystyle \sigma _{b}} respectively is: D s n = ( μ a − μ b ) ( σ a + σ
Signal-to-noise_statistic
German 155 mm self-propelled howitzer
AGM-Piranha IV 10×10 AAC (GDLS) the Archer (BAE Bofors), the CAESAR, and the Sigma. SIGMA 155 – (Israel) Archer artillery system – (Sweden) Unit cost is based
RCH_155
Construction in differential topology
\sigma (x),\sigma '(x))d(\sigma '(x))\\&=a(x,\sigma (x),\sigma '(x))dx+b(x,\sigma (x),\sigma '(x))\sigma '(x)dx+c(x,\sigma (x),\sigma '(x))\sigma ''(x)dx\\&=[a(x
Jet_bundle
Algebra associated to any vector space
}}\sum _{\sigma \in {\mathfrak {S}}_{r+p}}\operatorname {sgn} (\sigma )t^{i_{\sigma (1)}\cdots i_{\sigma (r)}}s^{i_{\sigma (r+1)}\cdots i_{\sigma (r+p)}}{\mathbf
Exterior_algebra
American collegiate fraternity 1910–1985
merger with the Phi Sigma Kappa (ΦΣΚ) fraternity. In 1985, most Phi Sigma Epsilon chapters participated in the merger. Phi Sigma Kappa incorporated many
Phi_Sigma_Epsilon
Mathematical framework for investment risk
{\displaystyle \sigma _{p}^{2}=w_{A}^{2}\sigma _{A}^{2}+w_{B}^{2}\sigma _{B}^{2}+w_{C}^{2}\sigma _{C}^{2}+2w_{A}w_{B}\sigma _{A}\sigma _{B}\rho _{AB}+2w_{A}w_{C}\sigma
Modern_portfolio_theory
{\begin{aligned}f(\sigma _{1}(a),\sigma _{1}(a^{*}),\sigma _{1}(aa^{*}),\sigma _{1}(a^{*}a),&\cdots ,\sigma _{m}(a),\sigma _{m}(a^{*}),\sigma _{m}(aa^{*}),\sigma _{m}(a^{*}a))\\\leq
Universal representation (C*-algebra)
Universal_representation_(C*-algebra)
Measure of the "spread" of light in an optical system
{d} G_{\Sigma }=n^{2}\,\mathrm {d} \Sigma \cos \theta _{\Sigma }\,\mathrm {d} \Omega _{\Sigma }=n^{2}\,\mathrm {d} \Sigma \cos \theta _{\Sigma }{\frac
Etendue
System that converts an analog signal into a digital signal
can be implemented efficiently. A delta–sigma ADC (also known as a sigma–delta ADC) consists of a delta–sigma modulator followed by a digital filter.
Analog-to-digital_converter
Physical law in fluid mechanics
cos θ 1 + σ 2 cos θ 2 {\displaystyle \cos \theta _{c}=\sigma _{1}\cos \theta _{1}+\sigma _{2}\cos \theta _{2}} where θ 1 {\displaystyle \theta _{1}}
Cassie's_law
"Smallest" commutative algebra that contains a vector space
can be built as the quotient of the tensor algebra T(V) by the two-sided ideal generated by the elements of the form x ⊗ y − y ⊗ x. All these definitions
Symmetric_algebra
Element in a ring whose some power is 0
Pauli matrices σ ± = ( σ x ± i σ y ) / 2 {\displaystyle \sigma _{\pm }=(\sigma _{x}\pm i\sigma _{y})/2} . An operand Q {\displaystyle Q} that satisfies
Nilpotent
Strength of an object's radar echo
σ0 or σ0 ("sigma nought"), which is the average radar cross section of a set of objects per unit area: σ 0 = ⟨ σ A ⟩ {\displaystyle \sigma ^{0}=\left\langle
Radar_cross_section
Mixing (superposition) of atomic orbitals
N(s+{\sqrt {3}}p\sigma )} , where N is a normalisation constant (here 1/2) and pσ is a p orbital directed along the C-H axis to form a sigma bond. The ratio
Orbital_hybridisation
Type of analog-to-digital converter
temperature. As of 2012[update], SAR ADCs are limited to 18 bits, while delta-sigma ADCs (which can be 24 bits) are better suited if more than 16 bits are needed
Successive-approximation_ADC
American collegiate social fraternity
evolution of ideals and dedication to independence and freedom of choice. Former Phi Sigma Epsilon alumni were elected to serve as Phi Sigma Phi's first
Phi_Sigma_Phi
Collegiate and service organization
Sigma Alpha International (ΕΣΑ) is an International community and collegiate coeducational service organization. Established in 1929, Epsilon Sigma Alpha
Epsilon_Sigma_Alpha
Type of chemical reactor
the ideal PFR response. The variance associated with F(t) for a pulse stimulus into a cascade of CSTRs is σ t 2 = t ¯ 2 n {\displaystyle \sigma _{t}^{2}={\frac
Continuous stirred-tank reactor
Continuous_stirred-tank_reactor
Method of estimating the parameters of a statistical model, given observations
{\partial }{\partial \sigma }}\log {\Bigl (}{\mathcal {L}}(\mu ,\sigma ^{2}){\Bigr )}=-{\frac {\,n\,}{\sigma }}+{\frac {1}{\sigma ^{3}}}\sum _{i=1}^{n}(\
Maximum_likelihood_estimation
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SIGMA IDEAL
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