this post was submitted on 17 Jan 2024
40 points (82.3% liked)

No Stupid Questions

35920 readers
1107 users here now

No such thing. Ask away!

!nostupidquestions is a community dedicated to being helpful and answering each others' questions on various topics.

The rules for posting and commenting, besides the rules defined here for lemmy.world, are as follows:

Rules (interactive)


Rule 1- All posts must be legitimate questions. All post titles must include a question.

All posts must be legitimate questions, and all post titles must include a question. Questions that are joke or trolling questions, memes, song lyrics as title, etc. are not allowed here. See Rule 6 for all exceptions.



Rule 2- Your question subject cannot be illegal or NSFW material.

Your question subject cannot be illegal or NSFW material. You will be warned first, banned second.



Rule 3- Do not seek mental, medical and professional help here.

Do not seek mental, medical and professional help here. Breaking this rule will not get you or your post removed, but it will put you at risk, and possibly in danger.



Rule 4- No self promotion or upvote-farming of any kind.

That's it.



Rule 5- No baiting or sealioning or promoting an agenda.

Questions which, instead of being of an innocuous nature, are specifically intended (based on reports and in the opinion of our crack moderation team) to bait users into ideological wars on charged political topics will be removed and the authors warned - or banned - depending on severity.



Rule 6- Regarding META posts and joke questions.

Provided it is about the community itself, you may post non-question posts using the [META] tag on your post title.

On fridays, you are allowed to post meme and troll questions, on the condition that it's in text format only, and conforms with our other rules. These posts MUST include the [NSQ Friday] tag in their title.

If you post a serious question on friday and are looking only for legitimate answers, then please include the [Serious] tag on your post. Irrelevant replies will then be removed by moderators.



Rule 7- You can't intentionally annoy, mock, or harass other members.

If you intentionally annoy, mock, harass, or discriminate against any individual member, you will be removed.

Likewise, if you are a member, sympathiser or a resemblant of a movement that is known to largely hate, mock, discriminate against, and/or want to take lives of a group of people, and you were provably vocal about your hate, then you will be banned on sight.



Rule 8- All comments should try to stay relevant to their parent content.



Rule 9- Reposts from other platforms are not allowed.

Let everyone have their own content.



Rule 10- Majority of bots aren't allowed to participate here.



Credits

Our breathtaking icon was bestowed upon us by @Cevilia!

The greatest banner of all time: by @TheOneWithTheHair!

founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[โ€“] Lafari@lemmy.world 1 points 10 months ago (2 children)

I think I understand now, but what has left me scratching my nose (metaphorically):

Why is it called "B if and only if A", if what it really means is "B only if A and vice versa"? (Am I correct in thinking that's what it means?)

I just don't understand how that translates grammatically. To me, "B if and only if A" sounds the same as "B only if A". I can accept that they mean different things in the context of logic, just like I can assign any meaning to any label, like I could say that "dog" now means "kite" in a certain context. But it seems unintuitive and doesn't really make sense to me. Does that make sense?

[โ€“] jbrains@sh.itjust.works 2 points 10 months ago* (last edited 10 months ago)

"B if and only if A" is a shorthand way to write "B if A and B only if A". It's like how "He is young and thin" means "He is young and he is thin". We could write it the second way without trouble, but the first way is shorter, we agree that they mean the same thing, and we prefer to conserve energy when writing.

The form "if and only if" is merely a convenient shorthand. Shorthand is usually more convenient for the writer than for the reader. ๐Ÿคทโ€โ™‚๏ธ

Imagine these natural language sentences and analyze how they are different:

  • I'll go outside if it's not snowing
  • I'll go outside only if it's not snowing

Hint: what do you do in each case when it's snowing?

[โ€“] ook_the_librarian@lemmy.world 1 points 10 months ago* (last edited 10 months ago)

"If A then B" means if A is true, then B is guaranteed to be true. Note that if B is true and A is false, "if A then B" is still true.

"B only if A" means the only way for B to be true is for A to be true. It's weird, but it has the inverse truth table as "(not A) and B".