Totsugeki's Problems No. 2

[Renzo]

Difficulty: 2-star
Comment: Another basic problem. Should we be cautious of West two calls?
Round: East 1, 0 honba, dora

Scores: Everybody is 27,000. You are East.

East: You have discarded

Your hand


South: discards

The has been called by West for a 789 straight.

West: has called twice 789-crak and pon on white dragon. Discards


North: has discarded

The white dragon was ponned.

Citation: Totsugeki Touhoku, Oshiete! Kagaku suru maajan, Yousensha (2009), page 106.

Edit: Fixed the 15 tile problem and added the citation.

[Shirluban]

"Should we be cautious of West two calls?"
Considering his five first discards, it's unlikely he have half-flush, chanta, or shousangen. But he may have sanshouku (and dora).
It's also unlikely he'd open his hand for haku only.
So his hand range from 2 to 5 han.

Our riichi + dora hand don't really worth taking much risks, especially because it's a dead hand (15 tiles ).

[sasuraiger]

Two calls and West abruptly begins to throw middle tiles, starting with one close to the dora. He's got to have what he needs already: either one tile away or tenpai. I doubt that it's a big hand. I have more sets than I need, and this isn't an amazing hand. I'm getting rid of and working my way down the pin suit from there.

[Iapetus]

4-pin is both safe and the most efficient discard, so it's kind of a no-brainer for this turn. Those discards don't really say chanta or honitsu, but 789 sanshoku with the dora for 4000 is possible. The 889 shape discard will be the most risky one. However, we have 3 7-man so west's probably screwed on that too. Riichi chun dora 1 scores high enough to go for, but the shape isn't that good. Sanankou tsumo->haneman is a remote possibility.

[xKime]

I figure it would be cheating if I answer to this, given that not that long ago I've bought and pretty much memorized Totsugeki's book, including the problems. This book is seriously the best one out there, IMO.

Anyway, this is one of the few problems I actually got wrong the first time!

[Renzo]

Apologies for being away. I came back from X-mas and my supervisor wanted me to rewrite a lot of my thesis.

Answer is

I you have then you can accept making redundant.

From here you don't want to try to hope to draw . If you wanted that you should have discarded to begin with.
What you should aim for is pon dora 1, riichi dora 1 or riichi red dragon. But to get to menzen tempai is on average 10 turns so if the red dragon is discarded you should immediately call.