Cf: Genus, Species, Pie Charts, Radio Buttons • 1
Re: Minimal Negation Operators
Re: Laws of Form ( https://groups.io/g/lawsofform/topic/checkboxes/86874727
::: Bruce Schuman ( https://groups.io/g/lawsofform/message/1153
Leon Conrad's presentation talks about “marked” and “unmarked” states.
He uses checkboxes to illustrate this choice, which seem to be “either/or” (and not, for example, “both”).
Just strictly in terms of programming and web forms, if Leon does mean “either/or” — maybe he should use “radio buttons”
and not “checkboxes” […]
I posted an expanded and better-formatted version of my last message on my blog.
What programmers call “radio button logic” is related to what physicists call
“exclusion principles”, both of which fall under a theme from the first-linked
post above, suggesting that “taking minimal negations as primitive operators
enables efficient expressions for many natural constructs and affords a bridge
between boolean domains of two values and domains with finite numbers of values,
for example, finite sets of individuals”.
To illustrate, let's look at how the forms mentioned in the subject line have
both efficient and elegant representations in the cactus graph extension of
Peirce’s logical graphs and Spencer Brown’s calculus of indications.
Keeping to the existential interpretation for now, we have the following readings
of our formal expressions.
tabula rasa = true
( ) = false
(x) = not x
x y = x and y
(x (y)) = x ⇒ y
((x)(y)) = x or y
and so on.
Take a look at the following article on minimal negation operators.
Minimal Negation Operators
The cactus expression (x, y, z) evaluates to true
if and only if exactly one of the variables x, y, z is false.
So the cactus expression ((x),(y),(z)) says exactly one of the
variables x, y, z is true. Push one variable “on” and the other
two go “off”, just like radio buttons. Drawn as a venn diagram,
the proposition ((x),(y),(z)) partitions the universe of discourse
into three mutually exclusive and exhaustive regions.
Refer now to Table 1 at the end of the following article.
Logical Graphs • Appendices
Figure 1 shows the cactus graph for ((a),(b),(c)).
Figure 1. Cactus ((a),(b),(c))
Now consider the expression (x, (a),(b),(c)).
Figure 2 shows the cactus graph for (x, (a),(b),(c)).
Figure 2. Cactus (x, (a),(b),(c))
If x is true, i.e. blank, the expression reduces to ((a),(b),(c)),
so we have a partition of the region where x is true into three
mutually exclusive and exhaustive regions where a, b, c,
respectively, are true.
If x is false, it is the unique false variable,
meaning (a) and (b) and (c) are all true,
so none of a, b, c are true.
We can picture this as a pie chart where a pie x
is divided into exactly three slices a, b, c.
It is the same thing as having a genus x
with exactly three species a, b, c.