I resisted this earlier because it seems like you want to avoid learning math. But, it seems to me
that "screening off" is just a special (and less useful) example of what's called an
"articulation point" (or cut point) in graphs.
https://mathworld.wolfram.com/ArticulationVertex.html
Maybe if you replaced all the arrows with lines, the concept would be more
clear?
On 12/20/21 10:41, glen wrote:
Taken in reverse order:
3) Yes, with A ⇒ B ⇒ C, A is behind the screen we call B. But notice that with A ⇐ B ⇐ C,
B still screens off C. Flipping the arrows is one way to permute the sentence. Another
way to permute the sentence is: C ⇒ B ⇒ A. Instead of flipping the arrows, we flip the
sentence ... I suppose like the converse. The term "screening off" is a
meta-sentence. It's a sentence about sentences.
As long as there is only one path from C to A or from A to C, and that path is
mediated by the medium of B, then A and C are screened off by B.
2) Yes, it's unfortunate that we use "causal" in the way we do. Think of that
word as *ambiguous* and the way Sober uses it as a jargonal word that is unrelated to
English or other natural languages. (It's not. But it's best to think that way.)
1) I disagree. People write all sorts of weird sh¡t. ... like poetry. Who
writes that stuff? What the hell are they doing that for? Just confuse us? Pfft.
On 12/20/21 10:27, thompnicks...@gmail.com wrote:
My first objection is rhetorical. You don't write an abstract about collisions
to introduce a paper about forks, not, at least, without explaining yourself
somewhere in the article.
Second, as the "formula" for screening off, with all it's t1's and t2's and
t3's, would suggest that order of events is crucial for screening off.
“Pr(R at t1 | I at t2 ) = Pr(R at t1 | I at t2 & S at t1 )”
I have been trying to come up with a verbal version of this expression, a
project which bores the mathematicians in the group because, for them, the
expressions is just the meaning of the concept, and no words are necessary. But
I hope that as a person who lives in both worlds, you might comment on it.
Screening off means, where A==>B==>C, A has no effect on C other than its
effect via B
.-- .- -. - / .- -.-. - .. --- -. ..--.. / -.-. --- -. .--- ..- --. .- - .
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