If I post an answer now then that would be attacking teddy's comment : /

go for it

@AsafKaragila Go there!

I think he meant to write $g: Y \to X$.

@JonasTeuwen Not even if they pay me to.

You don't want to go to Sydney?

I don't want to go to an operator theory conference.

@MattN no it's fine as it is.

@AsafKaragila Don't worry. There is also harmonic analysis.

@JonasTeuwen Applied one, not the abstract kind of harmonic analysis.

@tb If $g$ goes from $X$ to $Y$ and $f$ is a function from $X$ to $R$ then $f \circ g$ is a type error.

That's not harmonic analysis.

What's not?

$f \circ g (x) = f ( g (x))$.

@MattN No: $X\, \xrightarrow{g} Y \xrightarrow{f}\, \mathbb{C}$

@AsafKaragila The "abstract" one. If it were, you wouldn't have to add "abstract".

@MattN but $f$ is a function on $Y$.

@tb True dat. Maybe I shouldn't fiddle with stuff I only just learned : ) But I'll do it anyway.

Do it. It is a fine exercise

I think that happened.

Sorry

@tb Exactly what I thought : )

But a bit more dangerous than lhf.

:(

@JonasTeuwen So abstract algebra is not algebra?

Huh, extend results on BMO and unable to answer the question?

@AsafKaragila Abstract algebra is actually just algebra.

So abstract harmonic analysis is actually just harmonic analysis. What you call harmonic analysis is actually just "boring crap on the unit circle" :-D

Unit circle? No way.

@MattN No I don't think it's dangerous. Honest attempts are rarely downvoted. And I'm pretty confident that you can tackle it :)

To quote Adam Sandler/Rob Schneider from various films: "You can do it!! You can do it allll night long!!"

@tb Oh noes. I don't want to disappoint you : /

@MattN raaaaaaah encouragement $\neq$ pressure :)

Too late.

Hmm, the function H asks. If $f$ would be continuous, by limits everything is the same to $f(0)$, no?

So he's asking for a very ugly function.

Oh, right. Easy.

You're the one to talk

ROFL!!

Already stuck. Can I compute anything more accurate for $\| T \|$ than $\max_{y \in g(X)} |f(y)|$

Sure.

You can do anything you set your mind to! Except flying when doing PCP, you might think you can do that but you can't.

And that's not $\|T\|$ that's $\|T(f)\|$...

Did I understand the question? Maybe he wants one where the set of "bad points" is not of measure zero, but that is easy too if I'm not mistaken.

Jonas, all I'm taking from this comment is that a few days ago you were Jonas, then you were Joan S, now you're Janas. What's next? Xanax?

Cool.

It's one : )

yay!

I'm too slow : (

I wonder what new results on BMO this guy will find using that example...

@MattN I saw that 8-)!

Bloody monkey's.

Holy chickens.

:3912118 I am going to start a lodge called "Cough In" and people would come and cough inside then I will kick them out. Slowly, but surely, I will collect germs which will breed and in the dense environment the natural selection will eventually breed super bugs. Then I will take these super bugs and eradicate the entire east coast of the solar system.

I missed that^

I didn't :D.

Good night guys.

Was it important?

No.

@JonasTeuwen Night Jonas.

Good night, Jonas

Thanks.

Goodnight Janas.

@BrianMScott Hi

Hullo. Don’t expect coherence from me tonight: I’ve a bloody awful cold.

Actually, no. The sup of $f$ is one on $Y$. But it might not be one on $g(X)$.

Hi Brian

@BrianMScott Sounds bad : /

I am going to sleep.

@AsafKaragila Night Asaf!

@tb I saw your comment to Victor and figured that I’d look in here.

@MattN well, but now you take the sup over all $f$.

@MattN Gute Nacht.

@MattN The worst of it is that I couldn’t get out on the bike the last two days, and we’re having a record warm spell. :-(

Yep that's what I thought when I wrote that it's one. Then I forgot about it and made the previous mistake in thinking again.

@BrianMScott Yes, I was initially intending to be a bit harsher but it should remain in his inbox I've removed it already. He started doing this a few days ago.

@tb Thanks. : )

@BrianMScott Do you have fever?

@tb Did you see the interminable exchange I had with Hassan M. on that semigroups question? :-)

@Brian I hope you feel better. If you have to cough, I am breeding super bugs.

Farewell.

@AsafKaragila I saw that. And yes, I’m coughing, though not so badly as yesterday.

Did you save me some of the sputum?

@tb A bit; up to a couple of degrees (F) earlier this evening.

@AsafKaragila ’Fraid not.

Oh well.

Ciao!

Take it easy!

@tb And I don't think Watman shares your opinion.

@BrianMScott No, I haven't seen it grow that long. But in case you have a headache, it's probably not only the cold :)

I was getting ... distinctly frustrated. (As in: ‘There’s a mistake in the text? Wouldn’t be the first time; you’ll live!’)

@MattN Maybe. But it's not exactly down his ball park, so I wouldn't expect him to look that closely.

@BrianMScott I know the feeling...

Any idea what Robert Israel has against l’Hospital’s rule?

Maybe because it's one of the most subtle results in basic real analysis? I don't know.

Maybe it's also because some people seem to think that the definition of the derivative involves l'Hospital's rule :)

I remember that one; when I first saw the answer, I was so sure that he wasn’t using l’H. rule! (And knew it, I mean.)