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ethymology of symbols	ethymology of keywords
Location: http://members.tripod.de/s_ulf/csh/ethym-sym.html. By Ulf Schünemann since 070300. Please mail any comments.

Ethymology of Symbols

Disclaimer: This list is very incomplete.
Ordered lexically by the symbol's name

"" (juxtaposition): for logical conjunction (OR) and relational conjunction (composition) by DeMorgan 1860(?) (UK), Schröder 1895 (Germany).
"ć" ligature = a + e: in use since Merowingian time [dtv].
"&" (ampersand): logical AND in BCPL end of 1960s
"^" (and, logical conjunction): introduced by Alfred Tarski (1902-1983).
"'" (apostrophy, aka single quote):
1. line comment in Basic.
2. string literal up to space in Scheme.
3. character literal up to closing "'" in C/C++/Java.
4. part of identifiers in ML, Haskell.
"" (arrow down): the Peirce arrow is the logical symbol for NOR
(arrow up): exponentiation in Algol-60 1958-60 [HN].
In the later development of character sets, the caret character "^" came to be used instead of an up-arrow.
"|-" (assertion sign): combines with a statement (proposition) A to the judgement "|- A" which asserts/affirms A (read ``A is true''). The sign must have originated some time between Frege and Russell: ŤIn Russell's hands, ... the combination of Frege's Urteilsstrich, `judgement stroke', and Inhaltsstrich, `content stroke', came to be called the `assertion sign'ť [Löf].
":=" (assignment operator): Algol 58[ref]
"@" (at): address-of operator in BCPL end of 1960s
"*" (asterisk).
- The Kleene star in regular expression, introduced by Stephen Kleene (USA, 1909-1994).
"**" (asterisk asterisk) for exponentiation: John Backus' Fortran 1954-57, PL/1 [1970?], Ada 1978-83 [HN].
"|" (bar) -- see stroke.
"o" (circle) at end of associciation line: cardinality "optional": in IE notation [when?]
"^" (caret, circumflex, hat):
- the substitute for Algol-60's up-arrow for exponentiation in character sets without it
- bit-wise xor in C/C++/Java.
":" (colon):
1. as proportion symbol (at least) used since Stampioen de Jonghe (1610-90, Netherlands).
2. as division symbol used by Leibniz 1678/79 (Germany).
"<>" (diamond) at end of association line: hollow for shared-aggregation, filled for composition: in UML 1.x [ORM8]
"÷" (``Pell's division symbol''): introduced by Johann Heinrich Rahn 1659 (Swiss).
"$" (dollar) for accessing an ADT module's operations: CLU 1977 [PL]
"." (dot):
1. as decimal point introduced by Pellos 1492.
2. record field access, first in Algol(?),
3. for accessing a ((class) module) instance's operations: Simula 1967 [Sim], Euclid 1977 [PL] ...
"" (element-of, aka belongs, in): introduced by Guiseppe Peano (Italy, 1858-1932).
"=" (equivalence symbol): invented by Robert Recorde 1557 (GB).
"!" (exclamation mark):
1. dereference pointer in BCPL end of 1960s
2. logical negation in C/C++/Java.
3. line comment in X Resource files.
"" (existence quantor, reversed "E"): invented by Guiseppe Peano (Italy, 1858-1932).
Fork symbol (crow's foot) at end of association line: cardinality "many": by Gordon Everest [when?] (see also IE)
">" (greater than): invented by Thomas Harriot 1585.
"#" (hash, aka number sign, sharp):
1. line comment in Unix command languages.
2. preprocessor directives in C/C++.
"" (infinity sign):
1. for equivalence before Robert Recorde's "=" of 1557. E.g. by medieval William of Sherwood (c.f. Note 1 in [RTDU])
2. for infinity ...
"" (integral sign): introduced by Leibniz 1675 (Germany).
"" (intersect) by Guiseppe Peano (Italy, 1858-1932) (for logical conjunction (AND) ???)
"<" (less than): invented by Thomas Harriot 1585 (UK).
"<<" (less less): shift left bitwise in BCPL end of 1960s
"-" (minus sign): used for subtraction by Johannes Widman 1489 (Germany).
"--" (minus minus):
1. decrement operator in C/C++/Java.
2. line comment in ML, Ada, Eiffel, Haskell.
"×" (multiplication cross): introduced by William Oughtred 1631.
"^." (multiplication dot): introduced by Johann Müller Regiomontanus (Germany).
"#" (number sign) -- see hash.
"))" (parenthesis open, twice): for < by DeMorgan 1860 (UK).
"(* ... *)" (parenthesis asterisk ... asterisk parenthesis): comment in Pascal, and Prolog.
"%" (percent):
1. subscripting: a % 3 stands for a_i in BCPL end of 1960s
2. line comment in Prolog 1972 and TeX.
3. modulo (remainder of division) operator in C/C++/Java.
4. print argument format specification in Unix command languages and C.
"" (pi): for the diameter:circumfence proportion used by William Jones 1706 [TEP].
"+" (plus sign):
1. addition: Johannes Widman 1489 (Germany).
2. logical OR: Peirce 1870 (USA).
"'" ((single) quote) -- see apostrophy.
[] Rectangles for entities/classes with the name inside and, optionally, a compartment below with attributes: IE notation [when?]
";" (semicolon):
1. for relation composition by Schröder 1895 (Germany).
2. line comment in assembly languages and Scheme.
3. declaration and statement separator in Algol(?), Pascal, Ada, etc.
4. declaration and statement terminator in C/C++/Java.
"#" (sharp) -- see hash.
"/" (slash):
1. for relation residual, one of the earliest is Lambek 1958
"/* ... */" (slash asterisk ... asterisk slash): comment in C/C++/Java, and ML.
"" (square root symbol) invented by Michael Stifel (Germany, 1487-1567).
"**" (star star) -- see asterisk asterisk.
"|" (stroke, bar):
1. the Scheffer stroke is the logical symbol for NAND.
2. logical OR: in BCPL end of 1960s
3. bit-wise OR: C/C++/Java.
4. remainder of division: APL 1962 [TSPL]
5. cardinality "mandatory" for a stroke at the end of an associciation line: in IE notation [when?]
"" (subset) by Guiseppe Peano (Italy, 1858-1932) for implication ("C" = consequence???)
"" (union) by Guiseppe Peano (Italy, 1858-1932) (for logical disjunction (OR) ???)

Location: http://members.tripod.de/s_ulf/csh/ethym-sym.html
By Ulf Schünemann since 070300.
Please mail any comments.