Cf: Peirce’s 1870 “Logic of Relatives” • Comment 11.8
https://inquiryintoinquiry.com/2014/05/06/peirces-1870-logic-of-relatives-c…
Peirce’s 1870 “Logic of Relatives” • Comment 11.8
https://oeis.org/wiki/Peirce%27s_1870_Logic_Of_Relatives_%E2%80%A2_Part_2#C…
All,
Let’s take a closer look at the “numerical incidence properties” of relations,
concentrating on the assorted regularity conditions defined in the article on
Relation Theory (
https://oeis.org/wiki/Relation_theory ).
For example, L has the property of being “c-regular at j” if and only if
the cardinality of the local flag L_{x @ j} is equal to c for all x in X_j,
coded in symbols, if and only if |L_{x @ j}| = c for all x in X_j.
In like fashion, one may define the numerical incidence properties
“(< c)-regular at j”, “(> c)-regular at j”, and so on. For ease of
reference, a number of such definitions are recorded below.
Display 1. Definitions
https://inquiryintoinquiry.files.wordpress.com/2022/02/lor-1870-comment-11.…
Clearly, if any relation is (≤ c)-regular on one of its domains X_j and
also (≥ c)-regular on the same domain, then it must be (= c)-regular on
that domain, in short, c-regular at j.
For example, let G = {r, s, t} and H = {1, 2, 3, 4, 5, 6, 7, 8, 9}
and consider the dyadic relation F ⊆ G × H bigraphed below.
Figure 38. Dyadic Relation F
https://inquiryintoinquiry.files.wordpress.com/2014/05/lor-1870-figure-38.j…
We observe that F is 3-regular at G and 1-regular at H.
Regards,
Jon