Friday, June 30, 2017

Symmetry group - Wikipedia

Symmetry group - Wikipedia: "The proper symmetry group of an object is equal to its full symmetry group if and only if the object is chiral (and thus there are no orientation-reversing isometries under which it is invariant)."



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Wednesday, June 28, 2017

Functional (mathematics) - Wikipedia

Functional (mathematics) - Wikipedia: "Richard Feynman used functional integrals as the central idea in his sum over the histories formulation of quantum mechanics. This usage implies an integral taken over some function space.
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Sunday, June 25, 2017

Indefinite orthogonal group - Wikipedia

Indefinite orthogonal group - Wikipedia: "In mathematics, the indefinite orthogonal group, O(p, q) is the Lie group of all linear transformations of an n-dimensional real vector space that leave invariant a nondegenerate, symmetric bilinear form of signature (p, q), where n = p + q. The dimension of the group is n(n − 1)/2.
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Lagrangian (field theory) - Wikipedia

Lagrangian (field theory) - Wikipedia: "Often, a "Lagrangian density" is simply referred to as a "Lagrangian".
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Saturday, June 17, 2017

Killing form - Wikipedia

Killing form - Wikipedia: "in many cases, the Killing form can be used as a metric tensor on a manifold,"



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Thursday, June 15, 2017

Exponential map (Lie theory) - Wikipedia

Exponential map (Lie theory) - Wikipedia: " is the multiplicative group of positive real numbers (whose Lie algebra is the additive group of all real numbers). "



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Wednesday, June 14, 2017

Representation theory of the Lorentz group - Wikipedia

Representation theory of the Lorentz group - Wikipedia: "Mathematically the Lorentz group is defined as the set of transformations preserving the bilinear form
{\displaystyle (ct_{1},x_{1},y_{1},z_{1})\cdot (ct_{2},x_{2},y_{2},z_{2})=-c^{2}t_{1}t_{2}+x_{1}x_{2}+y_{1}y_{2}+z_{1}z_{2},} "



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Friday, June 09, 2017

Adjoint representation - Wikipedia

Adjoint representation - Wikipedia: "linearizing (i.e. taking the differential of) the action of G on itself by conjugation. The adjoint repre"



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Saturday, June 03, 2017

Friday, June 02, 2017

Home - Quora

Home - Quora: "‘At’ is a preposition to do with location. It can be a location in space or time.

at = means the action takes place for the period of the time stated.

It can be at a time as referenced by a clock (9pm) or a period of time (night).

In is a preposition to do with containment. We use it with time to indicate an action that happens within a time period.

In other words:

‘At night’ IS the time period something happens

‘In the night’ CONTAINS the time period that something happens.
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