[FRIAM] Dear Long Suffering Colleagues

[glen]

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, thompnickson2 at 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