Suji are a popular defense strategy; so popular, in fact, that suji traps are an effective anti-defense. We would like to increase the yomi level and create an anti-anti-defense by identifying when suji traps are likely. Are there situations in which suji are more dangerous? Are they really traps, or are they just incidental discards?
Prominent authors actually disagree on this. Some claim that suji discarded after riichi are more dangerous, while others claim that suji discarded before riichi are more dangerous. The general agreement is that the tile discarded immediately upon declaring riichi is dangerous.
Who’s right? Do you think there’s a difference? Using the Tenhou game logs database, we can examine riichi hands and their discards to finally answer this question.