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A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Many other names have been used for this set, and its borders are not agreed on. Precious metals – Variously-defined group of non-radioactive metals of high economical value. Superactinides – Hypothetical series of elements 121 to 157, which includes a predicted "g-block" of the periodic table.
In mathematics, and more specifically in order theory, several different types of ordered set have been studied. They include: Cyclic orders, orderings in which triples of elements are either clockwise or counterclockwise; Lattices, partial orders in which each pair of elements has a greatest lower bound and a least upper bound.
At the time the systematic names were recommended (1978), names had already been officially given to all elements up to atomic number 103, lawrencium. While systematic names were given for elements 101 ( mendelevium ), 102 ( nobelium ), and 103 (lawrencium), these were only as "minor alternatives to the trivial names already approved by IUPAC ...
The partially ordered set on the right (in red) is not a tree because x 1 < x 3 and x 2 < x 3, but x 1 is not comparable to x 2 (dashed orange line). A tree is a partially ordered set (poset) (T, <) such that for each t ∈ T, the set {s ∈ T : s < t} is well-ordered by the relation <. In particular, each well-ordered set (T, <) is a tree.
Set 3-1 has three possible versions: [0 1 1 1 2 T], [0 1 1 T E 1], and [0 T T 1 E 1], where the subscripts indicate adjacency intervals. The normal form is the smallest "slice of pie" (shaded) or most compact form, in this case: [0 1 1 1 2 T]. This is a list of set classes, by Forte number. [1]
Smith–Volterra–Cantor set, also called the fat Cantor set − A closed nowhere dense (and thus meagre) subset of the unit interval [,] that has positive Lebesgue measure and is not a Jordan measurable set. The complement of the fat Cantor set in Jordan measure is a bounded open set that is not Jordan measurable.
The enormous number of varieties of the cultivated European pear (Pyrus communis subsp. communis), are likely derived from one or two wild subspecies (P. c. subsp. pyraster and P. c. subsp. caucasica), widely distributed throughout Europe, and sometimes forming part of the natural vegetation of the forests.