What is ∀?

[daveloyall]

...And other symbols found in http://enigma.media.mit.edu/enigma_full.pdf ?

[LOZORD]

It usually means for all. A backwards 'E' means for some or there exists.
For a set S = { s1, s2, s3 ..., sn }:
For all <stmt> in S can be represented as stmt(s1) AND stmt(s2) AND stmt(s3) AND ... AND stmt(sn)
For some <stmt> in S can be represented as stmt(s1) OR stmt(s2) OR stmt(s3) OR ... OR stmt(sn)
Here's the code I would propose:

/* 
elements: a set (Array) of things
predicate: a function that takes one or more things from elements and returns true or false
*/
function forAll (elements, predicate) {
  return elements.every(predicate);
}

//And for backwards 'E' (existence)
function forSome (elements, predicate) {
  return elements.some(predicate);
}

It's nice that we can simply use functions already provided by JS! (Although it might be easier to do others in Haskell 😎)

Any other specific ones you want explained?

[pirate]

You should pull-request this so it's included in the main list.

[StoneCypher]

Programmers will generally think of the existential quantifier ∃ ∃ as "functional any."

Because JavaScript is required by law to get nothing right ever, JavaScript calls this some.

var isOdd = function(X) { return (x%2); },
    Example = [2,4,6,7];

window.alert(Example.some(isOdd));

[LOZORD]

Working on a PR now... plan to push in the next few days. I hope to include Set notation/theory as well.

@daveloyall I saw some statistical distribution notation in that article you shared. Would you like that explained as well?

[daveloyall]

@LOZORD sure, though I don't suggest prioritizing it on my behalf. That paper was just something I had on my screen at the moment I discovered this math-as-code project. ...There was some other paper that I care more about, I'll try to find it. Something like "Category Theory for Computer Scientists". Using this project, perhaps we can turn that paper into "Category Theory for Industry Programmers". :)

[allo-]

\Forall i \in X: Y(i) can be seen as

for i in X:
    assert Y(i)