In
logic and
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
, inclusion is the concept that all the contents of one object are also contained within a second object.
For example, if ''m'' and ''n'' are two
logical matrices, then
:
The modern symbol for inclusion first appears in
Gergonne
Joseph Diez Gergonne (19 June 1771 at Nancy, France – 4 May 1859 at Montpellier, France) was a French mathematician and logician.
Life
In 1791, Gergonne enlisted in the French army as a captain. That army was undergoing rapid expansion becau ...
(1816), who defines it as one idea 'containing' or being 'contained' by another, using the backward letter 'C' to express this.
Peirce articulated this clearly in 1870, arguing also that inclusion was a wider concept than equality, and hence a logically simpler one.
Schröder
Schröder (Schroeder) is a German language, German surname often associated with the Schröder family. Notable people with the surname include:
* Arthur Schröder (1892–1986), German actor
* Atze Schröder, stage name of German comedian Hubertu ...
(also
Frege) calls the same concept 'subordination'.
[Vorlesungen I., 127.]
References
1816 introductions
History of logic
Logic
{{logic-stub