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  2. Chemical purity - Wikipedia

    en.wikipedia.org/wiki/Chemical_purity

    ACS grade is the highest level of purity, and meets the standards set by the American Chemical Society (ACS). The official descriptions of the ACS levels of purity is documented in the Reagent Chemicals publication, issued by the ACS. [3] [4] It is suitable for food and laboratory uses. Reagent grade is almost as stringent as the ACS grade.

  3. Stratification (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Stratification_(mathematics)

    In New Foundations (NF) and related set theories, a formula in the language of first-order logic with equality and membership is said to be stratified if and only if there is a function which sends each variable appearing in (considered as an item of syntax) to a natural number (this works equally well if all integers are used) in such a way that any atomic formula appearing in satisfies ...

  4. New Foundations - Wikipedia

    en.wikipedia.org/wiki/New_Foundations

    NF 3 is the fragment of NF with full extensionality (no urelements) and those instances of comprehension which can be stratified using at most three types. NF 4 is the same theory as NF. Mathematical Logic (ML) is an extension of NF that includes proper classes as well as sets.

  5. Engineering drawing abbreviations and symbols - Wikipedia

    en.wikipedia.org/wiki/Engineering_drawing...

    A general note applies generally and is not called out with flags. 2. Find number: "FN" meaning "find number" refers to the ordinal number that gives an ID tag to one of the constituents in a parts list (list of materials, bill of materials). Thus "fasten using FN7" refers to a fastener that is "find number" 7 in the list. FoS: feature of size

  6. Glossary of mathematical jargon - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_mathematical...

    When used in this way, the stronger notion (such as "strong antichain") is a technical term with a precisely defined meaning; the nature of the extra conditions cannot be derived from the definition of the weaker notion (such as "antichain"). sufficiently large, suitably small, sufficiently close

  7. List of mathematical abbreviations - Wikipedia

    en.wikipedia.org/wiki/List_of_mathematical...

    def – define or definition. deg – degree of a polynomial, or other recursively-defined objects such as well-formed formulas. (Also written as ∂.) del – del, a differential operator. (Also written as.) det – determinant of a matrix or linear transformation. DFT – discrete Fourier transform.

  8. Academic grading in the United States - Wikipedia

    en.wikipedia.org/wiki/Academic_grading_in_the...

    The top grade, A, is given here for performance that exceeds the mean by more than 1.5 standard deviations, a B for performance between 0.5 and 1.5 standard deviations above the mean, and so on. [17] Regardless of the absolute performance of the students, the best score in the group receives a top grade and the worst score receives a failing grade.

  9. Noise figure - Wikipedia

    en.wikipedia.org/wiki/Noise_figure

    Noise figure (NF) and noise factor (F) are figures of merit that indicate degradation of the signal-to-noise ratio (SNR) that is caused by components in a signal chain.These figures of merit are used to evaluate the performance of an amplifier or a radio receiver, with lower values indicating better performance.