David G.

@VestaTian Well, you apparently have a systemd-ized write. :-( Could those people have invented a replacement for mesg y? The explanation of why /dev/pts/0 is accessed when you are writing to tty1 is simple: pts/0 is where you are, and write will tell the remote user where to write back.

The "not logged in" would seem to indicate records, not permission. You might try using strace ... as in strace -o/tmp/tracefile write vtian pts/0 ... though you might need some programming skill to analyze the tracefile. And while you say you ran as root, your prompt indicates non-root. On more thought: "vbox" could indicate "virtual box", and if so, and if you have mounted multiple /dev/pts directories, they could be independent.

1) Do you know what version of write you are using? (i.e. what package is it from.) 2) does it work if you try running as root? 3) Could your disk that write is on be mounted nosuid ?

I think the first vote I ever received was an unexplained down vote. People still up vote that answer occasionally.

[aside: @pranav, I did not downvote you, and have apparently lost two upvotes. :-( ]

that symmetry gets us that the red and green circles touch, and the green semicircle touches EC and BC.

the symmetry of the two greens is derived from the DEC triangle, HI, and FG.

only AB(before move),DE(after move), AC, the green semicircle are obviously tangent to the red circle.

and FG is tangent to both greens

DE from before the move is moved to FG...

HI is tangent to both greens, before and after move

AB moved to DE...

Lets see if this helps...

(and I guess I should state that the is reflexive symmetry around the line through the center of the red circle and the move lower left triangle corner. and ignores the fact that one circle is only a semicircle.)

and the fact that those two lines are equally far from the lines the green circle centers are on.

of the two green circles, that we get from the centers on the edges, and from their both being tangent to the upper horizontal line and the rightmost line parallel to the original left edge.

we get that from the symmetry, not the other way around.

Do you admit both are centered on the edge of the reduced triangle?

ah.

green circles?

Do you seen the circles being proven symmetric?

which includes the red circle and the far edge of the triangle.

\What one touches, the other touches, at least where the thing touched is symmetric

this, and the centers on the edge of the triangle, gives us symmetry between the two green green circles.

both green circles

The two lines intersecting the red circle are parallel to the edges now touching the red circle, and tangent to both circles.

I will admit I am sort of tempted to try to redo it as an animated SVG.... though I'm not sure SE would support it.

does call for the symmetry of the triangle too...

because we have symmetry and the green circle at the top right touches the right edge.

the line through the center of the green circle was the left edge of the triangle dragged right with the red circle it was tangent to, and the green semicircle.

wait....

ok, the dragged along side of the triangle is.

none of the added lines are tangent to the red...

Oh... the ONLY thing that is EVER tangent to the red circle are the sides of the triangles and the two green circles...

I will admit I went through a bunch of weird ideas... Adding a second red circle on the right... Adding a mirror image along the bottom. Alas, I couldn't find any way forward on those...

OK, I see the citation...

I saw your answer.... missing, but assuming, a number of points from mine...

I think this shows that the rest is all symmetric....

The two lines intersecting the red circle are symmetric, yes?

@Pranay I wouldn't have thought I needed to.... It is slid from the center the same amount the line that was tangent on the left moved right to meet the center. That makes it tangent on the right.

@Pranay Are the edits sufficient?

@Pranay equivalently, how do we know the red and green circles touch. The symmetry makes it both or neither. I am not sure. I believe it has to do with the fact that you can now slide the red and green circles down left to match the original tangent; or equivalently that the final line would be tangent to the original semicircle. The later can be shown by noting that the distance from the top of the green circle to the top if the triangle is the green radius, so we get a similar triangle with the tangent by copying the upper half to the lower half.

@Pranay Well, I started with OP's second picture, and copied the line. If you wish, (rot13: pbafvqre gung lbh zbir gur frzvpvepyr, erq pvepyr, naq yrsg yvar nyy ng bapr. Naq lbh pna zbir vg gvyy lbh ovfrpg gur hccre pvepyr naq rknzvar gur flzzrgel.)

less than 8 hours and 3 of 4 of my time servers have been culled when using pool. No more "pool" for me, except when using pool.ntp.org

@PaulGear will see if I can find anything noted here.

I should look again.

next time, 3-4 years ago I think, more like $300...

First time I went looking for NTP hardware, ~$3000, oven controlled crystals, etc...

version="ntpd [email protected] Wed Sep 23 11:46:38 UTC 2020 (1)",