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  2. Least-upper-bound property - Wikipedia

    en.wikipedia.org/wiki/Least-upper-bound_property

    More generally, one may define upper bound and least upper bound for any subset of a partially ordered set X, with “real number” replaced by “element of X ”. In this case, we say that X has the least-upper-bound property if every non-empty subset of X with an upper bound has a least upper bound in X.

  3. 2,2,2-Trifluoroethanol - Wikipedia

    en.wikipedia.org/wiki/2,2,2-Trifluoroethanol

    2,2,2-Trifluoroethanol is the organic compound with the formula CF 3 CH 2 OH. Also known as TFE or trifluoroethyl alcohol, this colourless, water-miscible liquid has a smell reminiscent of ethanol. Due to the electronegativity of the trifluoromethyl group, this alcohol exhibits a stronger acidic character compared to ethanol.

  4. Textbook - Wikipedia

    en.wikipedia.org/wiki/Textbook

    CK-12 FlexBooks are designed to facilitate conformance to national and United States and individual state textbook standards. CK-12 FlexBooks are licensed under a Creative Commons BY-NC-SA license. CK-12 FlexBooks are free to use online and offer formats suitable for use on portable personal reading devices and computers – both online and ...

  5. Chemistry - Wikipedia

    en.wikipedia.org/wiki/Chemistry

    Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.

  6. List of unsolved problems in mathematics - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Many mathematical problems have been stated but not yet solved. These problems come from many areas of mathematics, such as theoretical physics, computer science, algebra, analysis, combinatorics, algebraic, differential, discrete and Euclidean geometries, graph theory, group theory, model theory, number theory, set theory, Ramsey theory, dynamical systems, and partial differential equations.

  7. Letter frequency - Wikipedia

    en.wikipedia.org/wiki/Letter_frequency

    The California Job Case was a compartmentalized box for printing in the 19th century, sizes corresponding to the commonality of letters. The frequency of letters in text has been studied for use in cryptanalysis, and frequency analysis in particular, dating back to the Arab mathematician al-Kindi (c. AD 801–873 ), who formally developed the method (the ciphers breakable by this technique go ...

  8. Wacker process - Wikipedia

    en.wikipedia.org/wiki/Wacker_process

    Pd + 2 CuCl 2 + 2 Cl − → [PdCl 4] 2− + 2 CuCl 2 CuCl + ⁠ 1 / 2 ⁠ O 2 + 2 HCl → 2 CuCl 2 + H 2 O. Only the alkene and oxygen are consumed. Without copper(II) chloride as an oxidizing agent, Pd(0) metal (resulting from beta-hydride elimination of Pd(II) in the final step) would precipitate, stopping Philips' reaction after one cycle.

  9. Trigonometry - Wikipedia

    en.wikipedia.org/wiki/Trigonometry

    Trigonometry (from Ancient Greek τρίγωνον (trígōnon) 'triangle' and μέτρον (métron) 'measure') [1] is a branch of mathematics concerned with relationships between angles and side lengths of triangles.