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  2. Nullity (graph theory) - Wikipedia

    en.wikipedia.org/wiki/Nullity_(graph_theory)

    The nullity of M is given by m − n + c, where, c is the number of components of the graph and n − c is the rank of the oriented incidence matrix. This name is rarely used; the number is more commonly known as the cycle rank, cyclomatic number, or circuit rank of the graph. It is equal to the rank of the cographic matroid of the graph.

  3. Rank–nullity theorem - Wikipedia

    en.wikipedia.org/wiki/Rank–nullity_theorem

    The rank–nullity theorem is a theorem in linear algebra, which asserts: the number of columns of a matrix M is the sum of the rank of M and the nullity of M ; and the dimension of the domain of a linear transformation f is the sum of the rank of f (the dimension of the image of f ) and the nullity of f (the dimension of the kernel of f ).

  4. Oddo–Harkins rule - Wikipedia

    en.wikipedia.org/wiki/Oddo–Harkins_rule

    The Oddo–Harkins rule holds that an element with an even atomic number is more abundant than the elements with immediately adjacent atomic numbers. For example, carbon, with atomic number 6, is more abundant than boron (5) and nitrogen (7). Generally, the relative abundance of an even atomic numbered element is roughly two orders of magnitude ...

  5. Nullity theorem - Wikipedia

    en.wikipedia.org/wiki/Nullity_theorem

    More generally, if a submatrix is formed from the rows with indices {i 1, i 2, …, i m} and the columns with indices {j 1, j 2, …, j n}, then the complementary submatrix is formed from the rows with indices {1, 2, …, N} \ {j 1, j 2, …, j n} and the columns with indices {1, 2, …, N} \ {i 1, i 2, …, i m}, where N is the size of the ...

  6. Zero matrix - Wikipedia

    en.wikipedia.org/wiki/Zero_matrix

    There is exactly one zero matrix of any given dimension m×n (with entries from a given ring), so when the context is clear, one often refers to the zero matrix. In general, the zero element of a ring is unique, and is typically denoted by 0 without any subscript indicating the parent ring. Hence the examples above represent zero matrices over ...

  7. Atomic number - Wikipedia

    en.wikipedia.org/wiki/Atomic_number

    In the 19th century, the term "atomic number" typically meant the number of atoms in a given volume. [ 1 ] [ 2 ] Modern chemists prefer to use the concept of molar concentration . In 1913, Antonius van den Broek proposed that the electric charge of an atomic nucleus, expressed as a multiplier of the elementary charge , was equal to the element ...

  8. Neutronium - Wikipedia

    en.wikipedia.org/wiki/Neutronium

    Neutronium (or neutrium, [1] neutrite, [2] or element zero) is a hypothetical substance made purely of neutrons. The word was coined by scientist Andreas von Antropoff in 1926 (before the 1932 discovery of the neutron ) for the hypothetical "element of atomic number zero" (with no protons in its nucleus) that he placed at the head of the ...

  9. Hume-Rothery rules - Wikipedia

    en.wikipedia.org/wiki/Hume-Rothery_rules

    Hume-Rothery rules, named after William Hume-Rothery, are a set of basic rules that describe the conditions under which an element could dissolve in a metal, forming a solid solution. There are two sets of rules; one refers to substitutional solid solutions, and the other refers to interstitial solid solutions.