@Anoldmaninthesea. I did not want to digress to much from your original question in the other room so let me respond here.

On thing is oneboxing. Whenever you post a message which contains nothings just a link to a post, it is shown with a preview.

Like this:

And also if you use the format [title](url) that is better readable than the plain url. For example: If I write [Which links and sites are handled specially in chat?](https://meta.stackexchange.com/q/57286) then it is displayed like this in the chat message: Which links and sites are handled specially in chat?

Or in the case of your question I used [Why is $f(T)x=\frac{1}{2\pi i}\oint f(z)(z-T)^{-1}x \ dz$?](https://math.stackexchange.com/q/3431465) to get: Why is $f(T)x=\frac{1}{2\pi i}\oint f(z)(z-T)^{-1}x \ dz$?

ohhh!! thanks ;)

Oneboxed messages take more space, so they are not recommended in rooms which are busy. This is explicitly mentioned in the guidelines for the main chatroom: Main Chatroom Guidelines.

For rooms which have much less activity (which is the case for most of the area-specific room) this should be no problem.

I will also add that to get [text](url) I often use the bookmarklet "Link" from here. (I am linking to Wayback Machine - since the original site no longer works.)

And one general advice for situations when you're curious how somebody managed to do something in a chat message - you can simply look at the source: How to view/copy source of a message in chat?

For example, for my messages in the other room: chat.stackexchange.com/messages/52551181/history chat.stackexchange.com/messages/52551182/history

So much for chat-related issue.

Let's hope you find somebody who can help you with the actual mathematical question.

It might be useful to include some context - for example, saying where the claim you're trying to prove comes from.

Martin many thanks for all the links. I tried your answer from How to view/copy source of a message in chat?, but the history option doesn't seem to be available in your messages in this chat... only permalink is showing.

As to my question, I'm not sure which context is helpful... I'm learning by myself, and it's the first time I'm reading this subject. I'll add the reference to the question and some other things.

* and in permalink, we don't see the code.

@Anoldmaninthesea. The answer actually says (and also shows in the screenshot) that the "history link" is shown when you are in the chat transcript.

Sorry, I was distracted.

You can simply click on "permalink" - that gets you to the transcript. And then you can again use the manu to get to the history option.

I got it now. Thanks ;)

Have a great day! ;)

( i got to go now)