EZ

EZ or Ez may refer to:

Haplogroup E-Z827

In human genetics, E-Z827, also known as E1b1b1b, is the name of a major Y chromosome haplogroup. It is defined as the lineage which combines the haplogroups E-Z830 and E-V257, and defines their common ancestry. The former is predominantly found in the Horn of Africa and the Middle East, while the latter is most frequently observed in North Western Africa; it is also found at lower frequencies in Europe, and in isolated parts of Southeast Africa.

Subclades of E-Z827 and Distribution

Family Tree

The following phylogeny is based on the YCC 2008 tree and subsequent published research as summarized by ISOGG.

Z notation

The Z notation /ˈzɛd/ is a formal specification language used for describing and modelling computing systems. It is targeted at the clear specification of computer programs and computer-based systems in general.

History

In 1974, Jean-Raymond Abrial published "Data Semantics". He used a notation that would later be taught in the University of Grenoble until the end of the 1980s. While at EDF (Électricité de France), Abrial wrote internal notes on Z. The Z notation is used in the 1980 book Méthodes de programmation.

Z was originally proposed by Abrial in 1977 with the help of Steve Schuman and Bertrand Meyer. It was developed further at the Programming Research Group at Oxford University, where Abrial worked in the early 1980s, having arrived at Oxford in September 1979.

Abrial answers the question "Why Z?" with "Because it is the ultimate language!"

Usage and notation

Z is based on the standard mathematical notation used in axiomatic set theory, lambda calculus, and first-order predicate logic. All expressions in Z notation are typed, thereby avoiding some of the paradoxes of naive set theory. Z contains a standardized catalog (called the mathematical toolkit) of commonly used mathematical functions and predicates.

E-Z notation

E-Z configuration, or the E-Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry. It is an extension of cis/trans notation (which only describes relative stereochemistry) that can be used to describe double bonds having two, three or four substituents.

Following a set of defined rules (Cahn-Ingold-Prelog priority rules), each substituent on a double bond is assigned a priority.

If the two groups of higher priority are on opposite sides of the double bond, the bond is assigned the configuration E (from entgegen, German: [ɛntˈɡeːɡən], the German word for "opposite").

If the two groups of higher priority are on the same side of the double bond, the bond is assigned the configuration Z (from zusammen, German: [tsuˈzamən], the German word for "together").

The letters E and Z are conventionally printed in italic type, within parentheses, and separated from the rest of the name with a hyphen. They are always printed as full capitals (not lower case or small capitals), but do not constitute the first letter of the name for English capitalization rules (as in the example above). For organic molecules with multiple alkenes, it is sometimes necessary to indicate the alkene location for each E or Z symbol. For example, the chemical name of alitretinoin is (2E,4E,6Z,8E)-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexenyl)nona-2,4,6,8-tetraenoic acid, indicating that the alkenes starting at positions 2, 4, and 8 are E while the one starting at position 6 is Z.