Ippatsu: Difference between revisions

Ippatsu
Type	Yaku
Kanji	一発
English	One shot
Value	1 han
Speed	Riichi dependent
Difficulty	Luck

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Latest revision as of 22:36, 7 October 2024

Ippatsu 「一発」 is a yaku that is completely dependent on riichi. After declaring riichi, if the player wins before their next discard, and before anyone makes a tile call, ippatsu is scored. You must declare riichi to score ippatsu, so a hand can never have ippatsu by itself.

While ippatsu is generally considered to be a standard yaku, certain rulesets do not use it, in order to reduce variance and lower the value of a riichii. In general, when sitting down to play a game, ippatsu is counted unless otherwise specified or agreed on before the game.

Development

In order for ippatsu to be counted, the hand must win before the hand in riichi discards its next tile. The earliest possible chance to win with ippatsu comes from the shimocha's discard (player to the right). The latest possible chance to win with ippatsu is with the player's next drawn tile after the riichi declaration.

Furthermore, no interruption to the turn must occur. This means that tile calls will immediately end the chance for ippatsu. This includes any calls for kan except for a robbed kan (chankan). In sanma, the call for kita also denies ippatsu. If the riichi player declares kan or kita, ippatsu is still denied.

To repeat: even if a hand is won before the next discard, if a call is made, ippatsu is denied. Thus, players can purposefully make tile calls in order to disrupt another player's chance for ippatsu.

Examples

Ippatsu after kan.

Kan is called prior to the riichi call, and the hand wins on the next draw without interruption, so ippatsu is scored.

Ippatsu on discard

This hand wins on a discard before the next draw.

Ippatsu nullified

Ippatsu blocked by tile calls

In this example, the hand wins from an opponent discard before the next tile draw. However, two tile calls were made prior to the win, so ippatsu is not scored.

Compatibility

Main article: Yaku compatibility

	RCH	DRI	IPP	SMO	TAN	PFU	IPK	ITT	YAK	SDJ	SDO	TOI	SNA	SNK	CHA	JUN	RPK	SSG	HRO	HON	CHN	CHI	RIN	HAI	HOU	CHK
IPP

Ippatsu requires riichi (or double riichi), so it is impossible for a hand to score with ippatsu alone. At the very minimum, a hand could be riichi with ippatsu. Riichi and ippatsu are scored as separate yaku.

Unlike riichi, ippatsu cannot be combined with two yaku: rinshan kaihou and houtei raoyui. Rinshan requires a kan call (after declaring riichi), which would invalidate ippatsu. As for houtei, a riichi declaration must be made with at least 4 tiles left in the live wall. That leaves the very last possible tile draw (and discard) belonging to the riichi declarer.

Note that chankan is compatible with ippatsu. When winning off chankan, the kan call is interrupted, so ippatsu is retained.

With haitei

The last possible chance for riichi comes when there are eighteen tiles left in the walls, counting the fourteen tiles in the dead wall. That leaves four tiles left for regular player draws. After the last possible riichi, if no tiles are called, every player would have exactly one tile draw left. Therefore, the last tile would go to the riichi declarer, allowing both ippatsu and haitei to be scored. Naturally, players may make tile calls to disrupt both yaku.

References

↑ Ippatsu haitei (M.League 22-23, Mar.03 #1, East 3 Round 1 honba, North seat)

External links

一発

Ippatsu in Japanese Wikipedia

[1] Ippatsu haitei (M.League 22-23, Mar.03 #1, East 3 Round 1 honba, North seat)

[1]

@@ Line 10: / Line 10: @@
 }}
-'''Ippatsu''' {{kana|一発}} is a yaku completely dependent on [[riichi]].  By definition, ippatsu requires a riichi declaration to be in effect, for an additional 1 han.  Therefore, ippatsu cannot function as a stand-alone yaku.
+'''Ippatsu''' {{kana|一発}} is a yaku that is completely dependent on [[riichi]]. After declaring riichi, if the player wins before their next discard, and before anyone makes a [[tile call]], ippatsu is scored. You must declare riichi to score ippatsu, so a hand can never have ippatsu by itself.
-It is awarded if the player receives a winning tile within an uninterrupted set of opponent tile draws after the riichi declaration. The earliest possible chance to win with ippatsu comes from the shimocha's discard (player to the right).  The latest possible chance to win with ippatsu is with the player's next drawn tile after the riichi declaration.
+While ippatsu is generally considered to be a standard yaku, certain [[rule variations|rulesets]] do not use it, in order to reduce variance and lower the value of a riichii. In general, when sitting down to play a game, ippatsu is counted unless otherwise specified or agreed on before the game.
-While ippatsu is generally considered to be a standard yaku, certain [[rule variations|rulesets]] do not use it, in order to reduce variance and lower the value of a riichii. In general, when sitting down to play a game, ippatsu is counted unless otherwise specified or agreed on before the game.
+== Development ==
+In order for ippatsu to be counted, the hand must win before the hand in riichi discards its next tile. The earliest possible chance to win with ippatsu comes from the [[shimocha]]'s discard (player to the right). The latest possible chance to win with ippatsu is with the player's next drawn tile after the riichi declaration.
+Furthermore, no interruption to the turn must occur. This means that [[tile calls]] will immediately end the chance for ippatsu. This includes any calls for [[kan]] ''except'' for a robbed kan ([[chankan]]). In [[sanma]], the call for [[kita]] also denies ippatsu. If the riichi player declares kan or kita, ippatsu is still denied.
-== Cancellation ==
+To repeat: even if a hand is won before the next discard, if a call is made, ippatsu is denied. Thus, players can purposefully make tile calls in order to disrupt another player's chance for ippatsu.
-In order for ippatsu to be counted, the hand must win before the hand in riichi discards its next tile.  Furthermore, no interuption to the turn must occur.  [[Naki|Tile calls]] may immediately end the chance for ippatsu any time before the riichi declarer draws the next tile.  This includes any calls for [[kan]], except for a robbed kan ([[chankan]]).  In [[sanma]], the call for [[kita]] also interrupts and thus deny ippatsu.  Even if the hand wins before the next tile draw, ippatsu does not count if a tile call was made previously.  Thus, players may actually use the option to make tile calls to deliberately deny a player that chance for ippatsu.
 == Examples ==
@@ Line 23: / Line 25: @@
 * [http://tenhou.net/0/?log=2013061615gm-0089-0000-x380955c19e8f&tw=0&ts=3 Ippatsu] after [[kan]].
-:Kan is called prior to the riichi call; and the hand wins on the next draw without interruption.  Therefore, ippatsu is valid.
+:Kan is called prior to the riichi call, and the hand wins on the next draw without interruption, so ippatsu is scored.
 * [http://tenhou.net/0/?log=2014081719gm-0009-7447-73936980&tw=1 Ippatsu on discard]
@@ Line 32: / Line 34: @@
 * [http://tenhou.net/0/?log=2012110819gm-0009-7447-b68a0585&tw=2&ts=4 Ippatsu blocked] by [[Naki|tile calls]]
-In this example, the hand wins from an opponent discard before the next tile draw.  However, two tile calls were made prior to the win.  So, ippatsu is invalid here.
+In this example, the hand wins from an opponent discard before the next tile draw. However, two tile calls were made prior to the win, so ippatsu is not scored.
 == Compatibility ==
 {{main|Yaku compatibility}}
 {{Yaku compatibility table|IPP}}
-Ippatsu is unique among the yaku, for it requires riichi to even be applicable.  Because of this, it is impossible for a hand to score with ippatsu alone.  Ippatsu ''can'' combine with [[chankan]], as the kan call is not considered complete if someone wins off it.
+Ippatsu requires riichi (or double riichi), so it is impossible for a hand to score with ippatsu alone. At the very minimum, a hand could be riichi with ippatsu. Riichi and ippatsu are scored as separate yaku.
-At the very minimum, a hand could be riichi with ippatsu.  Unlike riichi, ippatsu is not compatible with every other yaku.  Two cannot mix with ippatsu: [[rinshan kaihou]] and [[houtei raoyui]].
+Unlike riichi, ippatsu cannot be combined with two yaku: [[rinshan kaihou]] and [[houtei raoyui]]. Rinshan requires a [[kan]] call (after declaring riichi), which would invalidate ippatsu. As for houtei, a riichi declaration must be made with at least 4 tiles left in the live wall. That leaves the very last possible tile draw (and discard) belonging to the riichi declarer.
-Regarding rinshan kaihou, the required call for [[kan]] to invoke rinshan already cancels out ippatsu.  With one single tile left in the regular wall, the last chance to call kan is allowable.  This may imply the rinshan draw as the "last possible tile draw".  However, that tile came from the dead wall as opposed to the regular wall, which is not the definition for the haitei.
+Note that [[chankan]] ''is'' compatible with ippatsu. When winning off chankan, the kan call is interrupted, so ippatsu is retained.
-As for houtei, a riichi declaration must be made with at least 4 tiles left in the live wall.  That leaves the very last possible tile draw (and discard) belonging to the riichi declarer.
+=== With haitei ===
+[[Image:Ippatsu haitei.png|thumb|250px|right|Winning hand of ippatsu haitei in [[M.League]].<ref>[https://www.youtube.com/watch?v=A6AeROpoJI4&t=391 Ippatsu haitei] (M.League 22-23, Mar.03 #1, East 3 Round 1 honba, North seat)</ref>]]
-===With haitei===
+The last possible chance for riichi comes when there are eighteen tiles left in the walls, counting the fourteen tiles in the dead wall. That leaves four tiles left for regular player draws. After the last possible riichi, if no tiles are called, every player would have exactly one tile draw left. Therefore, the last tile would go to the riichi declarer, allowing both ippatsu and haitei to be scored. Naturally, players may make tile calls to disrupt both yaku.
-[[Image:Last chance riichi.png|thumb|250px|right|Last chance to call riichi, with possible [http://tenhou.net/0/?log=2013062617gm-0089-0000-xa37799b6321c&tw=3&ts=4 Ippatsu] and [[haitei]].]]
-The last possible chance for riichi comes, when there are eighteen tiles left in the walls.  This counts the dead wall after a tile draw.  So, that leaves four tiles left for regular player draws; and barring any tile calling, every player would then have only one tile draw left.  For haitei then, the fourth remaining and last tile tile draw goes to the riichi caller.  Naturally, tile calls may occur beforehand to deny both the ippatsu and haitei chance.
+== References ==
+<references/>
 == External links ==