Saturday, 11 February 2012

Defence theory(15): Defence theory against two or more players(Continued)


This article continues the previous discussion about complicated situations.

At the beginning of a hand in a phoenix hanchan, the point spread is rather special. Toimen only has 1500 points, while I only lag behind shimocha by 2000 points in third place.

[First image in]

Originally, I had hoped to declare riichi with this hand. It's a good thing even if I knock out toimen and end up as second place. However, it was frightening when kamicha called 3 sets of tiles early in the game. Even though I knew that if kamicha had tsumo, I would end as third place, but because my hand was not in tenpai, I had to go into betaori.

Shimocha seeing this situation, naturally goes into betaori. The one you have to take special note of is toimen who is in fourth place. I followed kamicha's discard and discarded 7 wan, which toimen pon on, indicating that toimen is not in betaori. As I mentioned previously, attacking during situations where betaori is needed, is a sign of being in tenpai. Therefore not only do you have to defend against kamicha, you have to be careful of toimen.

I discarded the genbutsu of kamicha 7 sou, I draw 9 sou next. What should I discard?
[Second image in]

As both players have exposed melds, we can analyze it a little bit.

Let's talk about kamicha first. Kamicha called three sets of tiles early in the game, and has been discarding what he drew since the sixth discard. Obviously, he's in tenpai and his hand is not only worth 3900 points. (If kamicha's hand only has 3900 points, with this kind of points situation, there's no need to go into betaori.) Honitsu and toitoihou is the most likely here. In other words, kamicha has at least a mangan, even a 18000 points dealer haneman is possible, that's why it's frightening. As the discards of kamicha is too neat, we are unable to find out which suit he's waiting on. However since kamicha discarded quite a lot of pinzu early, the chances of a pinzu honitsu is the lowest. Also, in order to avoid toitoihou, you must avoid discarding any live tiles. Thus, the 8 and 9 sou in your hand is the most dangerous.

As for toimen, the hand is most likely a tanyao. Since dora was discarded, the value of the hand shouldn't be too high. It would be 3900 points even with aka-dora, the danger is low but you shouldn't be careless. Since you're in betaori, you might as well avoid dealing-in, although the main focus is on kamicha.

After some deliberation, I discarded 8 pin.

Although 8 pin is a live tile, it's also the suji-pai of toimen, giving it some degree of safety.
Kamicha discarded 7 and 9 pin earlier on, if kamicha had 7889 pin on the early stages, he wouldn't have discard 7 and 9 pin in a situation where honitsu is confirmed. Hence, we can conclude that kamicha discarded 7 and 9 pin while dismantling a taatsu. Since kamicha discarded 5 pin, a ryanmen wait on 58 pin is eliminated, thus 8 pin has a huge chance of passing.

Game Replay (Click on 全局牌譜 in
L0000 鳳南喰赤 平均R2070.2
1位 くるる(七段/R2010/+46) 3位 zeroRX(八段/R2137/-24) 4位 麦わらぼうし(七段/R2037/-36) 2位 kickchi(七段/R2097/+14) 

These sort of safe tile judging in betaori is not easy, as it involves a lot of analysis and theory. Also you'll need to pay attention to other players, to make the correct decision. These two articles can be said to be an example to show everyone what to focus on when finding safe tiles. If there are any more good examples in the future, they'll be posted to be shared with everyone.

The next article will be about some tricks to defending.
(To be continued)

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