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Q.E.D. or QED is an initialism of the Latin phrase quod erat demonstrandum, meaning "that which was to be demonstrated". Literally, it states "what was to be shown". [ 1 ] Traditionally, the abbreviation is placed at the end of mathematical proofs and philosophical arguments in print publications, to indicate that the proof or the argument is ...
In mathematics, the tombstone, halmos, end-of-proof, or Q.E.D. symbol "∎" (or " ") is a symbol used to denote the end of a proof, in place of the traditional abbreviation "Q.E.D." for the Latin phrase "quod erat demonstrandum". It is inspired by the typographic practice of end marks, an element that marks the end of an article. [1] [2]
QED – "Quod erat demonstrandum", a Latin phrase used at the end of a definitive proof. QEF – " Quod erat faciendum ", a Latin phrase sometimes used at the end of a geometrical construction. R
2. In geometry and linear algebra, denotes the cross product. 3. In set theory and category theory, denotes the Cartesian product and the direct product. See also × in § Set theory. · 1. Denotes multiplication and is read as times; for example, 3 ⋅ 2. 2. In geometry and linear algebra, denotes the dot product. 3.
In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. [ 1 ] [ 2 ] [ 3 ] In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. [ 2 ]
Q.E.D. (quod erat demonstrandum), used at the end of a mathematical proof Quantum electrodynamics , a field in particle physics QED manifesto and project, a database of mathematical knowledge
The ϕ 4 theory, QED, QCD, as well as the whole Standard Model all assume a (3+1)-dimensional Minkowski space (3 spatial and 1 time dimensions) as the background on which the quantum fields are defined. However, QFT a priori imposes no restriction on the number of dimensions nor the geometry of spacetime.
For example, renormalization in QED modifies the mass of the free field electron to match that of a physical electron (with an electromagnetic field), and will in doing so add a term to the free field Lagrangian which must be cancelled by a counterterm in the interaction Lagrangian, that then shows up as a two-line vertex in the Feynman diagrams.