I want to start by examining what I term 'Adjacent corner openings': that is openings of the form 1. a5 a1, where the initial stones are placed in corners of a single file or row. While I haven't seen this played too much online, it is an opening set that I think has a wide range of applications to other openings and a fair amount of intricacy.
Due to the breadth of possibilities, this needs to be divided even further, starting with the 'a-b' variations: 2. b1.
At this point the board looks like this:
[PTN: 1. a5 a1 2. b1]
At its core, this is a very aggressive opening. White is immediately drawing attention down the 1 row. It demands black to respond and counter. On the other hand, it risks influence and breathing room. If black fails to respond, white can easily mount pressure and possibly achieve an early victory - especially against novice players. Despite this, with strong play black can both mount a defense and take control of the situation.
To begin, any response from the 3-row and above is too passive.
For example, after 2. b1 c3 3. d1, white has a lot of pressure across the 1-row, while black has little room to defend for long, forcing black into early wall placement or captures.
[PTN: 1. a5 a1 2. b1 c3 3. d1]
( 2.b1 d3 3.c1 is pretty similar).
Some of the most common and strongest responses, are on the 2-row.
2. ... c2, for example, is one of the most straightforward moves - and perhaps common amongst novices. This builds an immediate response to the 1-row threat, while building some basic influence. Despite this, it may not be strong enough.
If 3. c1, then 3. ... d1 is a pretty decent response, cutting white's line and advancement, while gaining influence on d2 - which creates some potential pressure on the c and d files.
[PTN: 1. a5 a1 2. b1 c2 3. c1 d1]
However, white's better move is 3. d1!. Now a 3. ... d2 isn't nearly as effective of a deterrent. White still has clear pressure down the 1-row. Furthermore, c1 is currently under white control. If black makes the mistake of moving in, then white can capture or cut with significant effect (3. ... c1 4. b2 or possibly 4. d1<).
[PTN: 1. a5 a1 2. b1 c2 3. d1 c1 4. b2]
or
[PTN: 1. a5 a1 2. b1 c2 3. d1 c1 4. d1<]
Perhaps the most interesting - and in my opinion the strongest response is 2. ... d2!
[PTN: 1. a5 a1 2. b1 d2]
From here, black has a pretty good response to any 1-file play.
For example: 3. c1 d1. This creates a precise straight cut, while creating a threat up the d aisle. And if white tries to run up the board, the a5 stone is in position to support cuts and plays along the 4-row.
[PTN: 1. a5 a1 2. b1 d2 3. c1 d1]
For 3. d1 e1. This is a really interesting opening that has a number of fighting options for black and white and I may dedicate a future post solely to this line. In short, though, it reduces white's influence on the 1-row, while establishing territory and influence towards the center. It's not as solid as the straight cut, and thus has a few potential weaknesses. That being said, I would classify this as 'beautiful'.
[PTN: 1. a5 a1 2. b1 d2 3. d1 e1]
And 3. e1 d1.
[PTN: 1. a5 a1 2. b1 d2 3. e1 d1]
White could opt, however to abstain from the 1-file and head up the center with 3. c2. But at this point, black has diverted white, and has some good options to respond, set up territory, and even make threats.
[PTN: 1. a5 a1 2. b1 d2 3. c2]
I want to end this by noting the influence of the a5 stone. While it may seem irrelevant, it has a few major impacts on the opening. First and foremost, it directs white's attention. In an opposite corner opening (1. a5 e1 / e5 a1), if white chose, they could aggress either direction or both. Secondly, the a5 stone is able to help support black if white attempts to ascend the b or c files.
Next time I plan on exploring the 3. d1 e1 line further. By that point, I hope to come up with a name for that specific line.
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Think with mind of air
Listen close to heart of stone
A beautiful game
