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An astroid as the envelope of the family of lines connecting points (s,0), (0,t) with s 2 + t 2 = 1. The following example shows that in some cases the envelope of a family of curves may be seen as the topologic boundary of a union of sets, whose boundaries are the curves of the envelope.
A drawing of a butterfly with bilateral symmetry, with left and right sides as mirror images of each other.. In geometry, an object has symmetry if there is an operation or transformation (such as translation, scaling, rotation or reflection) that maps the figure/object onto itself (i.e., the object has an invariance under the transform). [1]
For the person interested in tilings and patterns, Visions of Symmetry provides many beautiful examples (which illustrate the theory expounded in Grünbaum and Shepard's Tilings and patterns [1987])." [8] J. Kevin Colligan reviewing the book for The Mathematics Teacher wrote: "This book sits on the boundary between mathematics and art, as did ...
This considerably complicates efforts to test string theory because there is an astronomically high number—10 500 or more—of configurations that meet some of the basic requirements to be consistent with our world. Along with the extreme remoteness of the Planck scale, this is the other major reason it is hard to test superstring theory.
In the first chapter, entitled Patterns with Classical Symmetry, the author introduces the concepts of motif, symmetry operations, lattice and unit cell, and uses these to analyze the symmetry of 13 of Escher's tiling designs. In the second chapter, Patterns with Black-white Symmetry, the antisymmetry operation (indicated by a prime ') is ...
This rolling-up is not normally referred to as "super". Thus, supergraded Lie superalgebras carry a pair of / ‑gradations: one of which is supersymmetric, and the other is classical. Pierre Deligne calls the supersymmetric one the super gradation, and the classical one the cohomological gradation. These two gradations must be compatible, and ...
In abstract harmonic analysis the notion of envelope plays a key role in the generalizations of the Pontryagin duality theory [20] to the classes of non-commutative groups: the holomorphic, the smooth and the continuous envelopes of stereotype algebras (in the examples given above) lead respectively to the constructions of the holomorphic, the ...
At low energies, type IIA string theory is described by type IIA supergravity in ten dimensions which is a non-chiral theory (i.e. left–right symmetric) with (1,1) d=10 supersymmetry; the fact that the anomalies in this theory cancel is therefore trivial.