so I think I will dig a bit into that fighting sequence to see why it was "urgent"
So let's come back to that game of Cho Chikun vs Sakata Eio and have a closer look at the fight that start here :
$$Wcm8
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 1 . . . X . . . |
$$ | . . O . . . . . . . . X . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$Wcm8
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 1 . . . X . . . |
$$ | . . O . . . . . . . . X . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
I didn't find any joseki starting like that (in Igowin Joseki and in josekipedia )?
but this move is not marked as a bad answer either... so what is that

an undefined move ?
Any way let's see the following moves....
$$Wcm8
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . a . . . . . . . . |
$$ | . . . , . . . . . , 2 1 3 . . B . . . |
$$ | . . O . . . . c b . . X . O 4 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$Wcm8
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . a . . . . . . . . |
$$ | . . . , . . . . . , 2 1 3 . . B . . . |
$$ | . . O . . . . c b . . X . O 4 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

is allready a surprise too me... I think I would have played at "a", "b"
but I see now that thw hoshi stone would be a bit alone then...
$$Wcm12
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . 4 X O O . . X . . . |
$$ | . . O . . . . . . 2 1 X . O X . . . . |
$$ | . . . . . . . . . . 3 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$Wcm12
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . 4 X O O . . X . . . |
$$ | . . O . . . . . . 2 1 X . O X . . . . |
$$ | . . . . . . . . . . 3 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
12 - 15 : ok
$$Wcm16
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . , . . . . . X X O O . . X . . . |
$$ | . . O . . . . . a X O X . O X . . . . |
$$ | . . . . . . . . 2 1 O 5 3 . . . . . . |
$$ | . . . . . . . . . 4 . . . . . . . . . |
$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$Wcm16
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . , . . . . . X X O O . . X . . . |
$$ | . . O . . . . . a X O X . O X . . . . |
$$ | . . . . . . . . 2 1 O 5 3 . . . . . . |
$$ | . . . . . . . . . 4 . . . . . . . . . |
$$ +---------------------------------------+[/go]
This

looks very small too me... I would have played "a" so I have something that is not correct in my judgement here...

ok, the lader at "a" doesn't work for white.

what if white tenuki... black would descend at

so I think this one was mandatory.

a forcing move

ok, mandatory too...
$$Bcm21
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 5 . 6 . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . 4 . X X O O . . X . . . |
$$ | . . O . . . . 2 3 X O X . O X . . . . |
$$ | . . . . . . . . X O O O O . 1 . . . . |
$$ | . . . . . . . . . X . . . . . . . . . |
$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$Bcm21
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 5 . 6 . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . 4 . X X O O . . X . . . |
$$ | . . O . . . . 2 3 X O X . O X . . . . |
$$ | . . . . . . . . X O O O O . 1 . . . . |
$$ | . . . . . . . . . X . . . . . . . . . |
$$ +---------------------------------------+[/go]

kill eye space in the bottom, and now I think that was also the idea behind

that is not just a forcing move...

looks weird to me... I don't really understand what white want to do here...
just threaten to cut at

? sure there is more then that... but I miss to spot the whole idea...

of course...

: still missing the plan... territory ? no... or not only but does that really help the other group ? seems to easy for black to separate...

separate....

set up a race to the center ? (and gain influance to attck the bottom/right corner ?
That's all for today... I will try to memorize these few moves as an exercice for and I will continue later...