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  2. Einstein problem - Wikipedia

    en.wikipedia.org/wiki/Einstein_problem

    In plane geometry, the einstein problem asks about the existence of a single prototile that by itself forms an aperiodic set of prototiles; that is, a shape that can tessellate space but only in a nonperiodic way. Such a shape is called an einstein, a word play on ein Stein, German for "one stone". [2]

  3. Quasicrystal - Wikipedia

    en.wikipedia.org/wiki/Quasicrystal

    The more precise mathematical definition is that there is never translational symmetry in more than n – 1 linearly independent directions, where n is the dimension of the space filled, e.g., the three-dimensional tiling displayed in a quasicrystal may have translational symmetry in two directions.

  4. Economic geology - Wikipedia

    en.wikipedia.org/wiki/Economic_geology

    Economic geology is concerned with earth materials that can be used for economic and industrial purposes. These materials include precious and base metals, nonmetallic minerals and construction-grade stone. Economic geology is a subdiscipline of the geosciences; according to Lindgren (1933) it is “the application of geology”.

  5. List of aperiodic sets of tiles - Wikipedia

    en.wikipedia.org/wiki/List_of_aperiodic_sets_of...

    A tiling that cannot be constructed from a single primitive cell is called nonperiodic. If a given set of tiles allows only nonperiodic tilings, then this set of tiles is called aperiodic . [ 3 ] The tilings obtained from an aperiodic set of tiles are often called aperiodic tilings , though strictly speaking it is the tiles themselves that are ...

  6. Aperiodic tiling - Wikipedia

    en.wikipedia.org/wiki/Aperiodic_tiling

    An aperiodic tiling is a non-periodic tiling with the additional property that it does not contain arbitrarily large periodic regions or patches. A set of tile-types (or prototiles) is aperiodic if copies of these tiles can form only non-periodic tilings. The Penrose tilings are a well-known example of aperiodic tilings. [1] [2]

  7. Glossary of geology - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_geology

    Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...

  8. Environmental determinism - Wikipedia

    en.wikipedia.org/wiki/Environmental_determinism

    His theory cited the natural environment and raw materials a civilization had as factors for success, instead of popular century-old claims of racial and cultural superiority. Diamond says that these natural endowments began with the dawn of man, and favored Eurasian civilizations due to their location along similar latitudes, suitable farming ...

  9. Non-representational theory - Wikipedia

    en.wikipedia.org/wiki/Non-representational_theory

    Non-representational theory is the study of a specific theory focused on human geography. It is the work of Nigel Thrift (Warwick University). [1] [2] The theory is based on using social theory, conducting geographical research, and the 'embodied experience.' [3]