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No reason to break up the iipeeko shape. No need for a 455 shape either, it increases our path to tenpai by just 4 tiles that don't get pinfu. The normal course here is to discard the red 5 man on tenpai for riichi/iipeiko, tanpin dora 1. But by keeping the 5-man, if we draw 4 or 6 man, we can drop the 34 of bamboos and get tanpin dora 2 for a 11600 ron without riichi, or haneman tsumo without riichi if we get iipeeko.

Something I very nearly missed before posting my answer is that there is a 3m in our pond. This is important because if we draw 4m later, we'd be furiten for 3/6m. I don't know what our draw/discard sequence up this point was, but I should say I probably wouldn't have discarded the 3m if the red 5m had been in my hand. I would have kept the 3-5-7 shape with a red 5 in the middle, but for this hand I can't say if that was the case or not.

Anyway, with this hand, there are five obvious potential sources of han:

• The red 5m
• The red 5p
• Pinfu
• Tanyao
• Iipeko

Tanyao and the red 5p are pretty much assured to be in the final hand. The three han sources up for contention are the red 5m, pinfu, and iipeko. If we discard the 2p, then we still have a pretty easy pinfu, and a good shot at iipeko. Further, the red 5m is still in our hand, so we haven't completely given up on it if we draw a 5m or 6m. If we do turn the [577]m shape into [567]m, thus losing our pair, we can either wait for the [5677]m or the [34]b shape to yield a pair, which would give us the best value hand, or we can discard the 3p and wait shapon with [4455]p if we need the hand to move faster.

By looking only which tiles makes us tenpai for which yaku, we have (unless I've overseen something):

Discard 5m ->
tanpin+red 25s 36p (3 han)
tanyao+red: 7m 5p (2 han)

Discard 7m ->
tanpin+redred: 6m (4 han)
tanyao+redred: 25s (3 han)

Discard 3s/4s ->
nada. Why have I listed them in the pool?

Discard 2p ->
tanpin+red+(ii): 25s (3/4 han)
tanpin+red+ii: 3p (4 han)
tanpin+red: 6p (3 han)

Discard 4p ->
tanpin+redred: 6m (4 han)
tanyao+red: 7m 5p (2 han)
tanyao+redred: 25s (3 han)

So discarding 5m gives the most tiles to be tenpai*, but for the cheapest hands.
While discarding 2p gives the second-most tiles to be tenpai*, and the best value.

* Considering the case of discarding 2p and drawing a 6m leads to a nice iishanten with a lots of outs to be tenpai (and worthing 3 to 5 han +riichi), the agari% is probably better by discarding 2p anyway.

Red 5m. We're dealer, let's take the fastest and more straight road without deviating. When you start to deviate your hand gets weaker and you're more prone to make mistakes; it's a usual pattern; it'd be very common to draw 4m and get into furiten, holding on to that 5m for too long and dealing into someone with it, draw 6m and make a delicate choice again, etc. Take the simplest road, made others worry about the dealer discarding dora and take a stand on the widest tenpai chance. I wouldn't be worried about that the 4 extra tiles for tenpai don't give pinfu, as I'd still call any tile for tenpai. Lately people don't give too much attention to agari% and all they think about is "I want at least mangan, so I have to use every han point I can." I guess that is more fun, but not always brings a direct profit with it. I'd still respect that way of thinking, I wish I could think like that, but I'm more of a player who is happy with winning 2000pt 4 out of 5 times than winning 8000 points 1 out of 5 times, even if both are practically the same.

However, were this Jansou rules (where you get chips for every red 5, or in my case at Marchao Jansou the other day, 100 yen coins!), I'd say pinzu/dots. And, of course, call any tile for tenpai. Don't worry too much about menzen.

xKime wrote:I'd still call any tile for tenpai. Lately people don't give too much attention to agari% and all they think about is "I want at least mangan, so I have to use every han point I can." I guess that is more fun, but not always brings a direct profit with it. I'd still respect that way of thinking, I wish I could think like that, but I'm more of a player who is happy with winning 2000pt 4 out of 5 times than winning 8000 points 1 out of 5 times, even if both are practically the same.

I wouldn't say this hand has a 1/5 chance of scoring mangan. It's a double ryanmen iishanten on the 7th turn (+ the shanpon). Nobody has called anything yet and most discards are terminals and honors. Even with riichi, the winning chances are quite high, and with damaten it's at least 5800. This is the type of hand I see as the one to earn serious points with - the hand I try to stay as dealer for, the hand that earns the points I can protect with quick, cheap wins. The red 5 discard is good for this too - I'd think "I want to increase my waits because riichi tanyao dora 1 is at least 7700 and I want the best possible chances to win that", but thinking "I want to win this hand no matter the score" just doesn't cut it for me on this one.

Iapetus wrote:

xKime wrote:I'd still call any tile for tenpai. Lately people don't give too much attention to agari% and all they think about is "I want at least mangan, so I have to use every han point I can." I guess that is more fun, but not always brings a direct profit with it. I'd still respect that way of thinking, I wish I could think like that, but I'm more of a player who is happy with winning 2000pt 4 out of 5 times than winning 8000 points 1 out of 5 times, even if both are practically the same.

I wouldn't say this hand has a 1/5 chance of scoring mangan. It's a double ryanmen iishanten on the 7th turn (+ the shanpon). Nobody has called anything yet and most discards are terminals and honors. Even with riichi, the winning chances are quite high, and with damaten it's at least 5800. This is the type of hand I see as the one to earn serious points with - the hand I try to stay as dealer for, the hand that earns the points I can protect with quick, cheap wins. The red 5 discard is good for this too - I'd think "I want to increase my waits because riichi tanyao dora 1 is at least 7700 and I want the best possible chances to win that", but thinking "I want to win this hand no matter the score" just doesn't cut it for me on this one.

When I said the example of the 1/5 mangan I didn't mean this hand, lol. I mean the playing style in general. No matter if both options lead to the same average, I prefer taking the agari course.

Nevertheless, don't fret it, I think that digitally it's better to take pon-ten/chii-ten from that 7th draw and on, but it's very likely you'll draw menzen tenpai first. That's why playing without chips, I'd simply discard red 5; no real need to stick to it for dear life. Playing with chips, pinzu. I do want to get menzen tenpai, that's why I choose that widest discard. Don't think I just want to throw the hand away.

For data on the best timing to take chii/pon ten digitally, refer to here:

http://doraaka.exblog.jp/15926085/

The data is taken from tenhou's Phoenix room, so it might be a little bit questionable to some people (last place avoidance mahjong (pst, as if that mattered until about the south round)) but since most of the hands analyzed are somewhere between the middle I think it makes no difference. Well, if you consider this as a 8000+ hand when menzen, it's better to wait until the 11th turn, but meh, I love to renchan.

(Also, if I took my experience from today playing at a parlor in Umeda, it's a lot better to take the open hand tenpai with good shape and red dora. The faster you get tenpai, the more tsumo chances you get, and tsumo is +1 chip from all for each red dora, and even if you riichi people just fold and let you lose your turn as dealer (dealer only continues after winning), but they don't seem to mind dealing into open hands that much ･ﾟ･(つД｀)･ﾟ･ ｳｪ―ﾝ
ronron rules are different from parlor, but it's just a little bit of trivia.)

Anyway, the question was what to discard, and I chose the widest mangan course of red 5m. At some point I will want to call a tile for tenpai, but that's besides the point.