Cf: Peirce’s 1870 “Logic of Relatives” • Comment 11.10
https://inquiryintoinquiry.com/2014/05/07/peirces-1870-logic-of-relatives-c…
Peirce’s 1870 “Logic of Relatives” • Comment 11.10
https://oeis.org/wiki/Peirce%27s_1870_Logic_Of_Relatives_%E2%80%A2_Part_2#C…
All,
A dyadic relation F ⊆ X × Y which qualifies as
a function f : X → Y may then enjoy a number of
further distinctions.
Definitions
https://inquiryintoinquiry.files.wordpress.com/2022/02/lor-1870-comment-11.…
For example, the function f : X → Y shown below is neither
total nor tubular at its codomain Y so it can enjoy none of
the properties of being surjective, injective, or bijective.
Figure 40. Function f : X → Y
https://inquiryintoinquiry.files.wordpress.com/2014/05/lor-1870-figure-40.j…
An easy way to extract a surjective function from any function
is to reset its codomain to its range. For example, the range
of the function f above is Y' = {0, 2, 5, 6, 7, 8, 9}. If we
form a new function g : X → Y' that looks just like f on the
domain X but is assigned the codomain Y', then g is surjective,
and is described as a mapping onto Y'.
Figure 41. Function g : X → Y'
https://inquiryintoinquiry.files.wordpress.com/2014/05/lor-1870-figure-41.j…
The function h : Y' → Y is injective.
Figure 42. Function h : Y' → Y
https://inquiryintoinquiry.files.wordpress.com/2014/05/lor-1870-figure-42.j…
The function m : X → Y is bijective.
Figure 43. Function m : X → Y
https://inquiryintoinquiry.files.wordpress.com/2014/05/lor-1870-figure-43.j…
Regards,
Jon