If you clue a double bluff, must it include a promise?

[Mimer]

If you clue a double bluff, must it include a promise? My opinion is no, because it makes the double bluff considerably weaker (much less usable), but the common opinion seem to be that it has.

[Romain672]

You should look for the recent post here: https://boardgamearena.com/forum/viewtopic.php?t=48875

[Yeah r]

I think Mimer is asking a question about double bluff.

For example, in the first turn:
Alice clues David’s red 4 with the rank clue 4.
Then Bob plays the red 1 from the finesse position.
Cathy plays the yellow 1 from the finesse position.

David would assume his 4 might be black.
However, David sees Cathy holds a red 3 in her second slot, right behind the yellow 1 she just played.
He then realizes his 4 can also be red, since this play confirms someone has a red 3 in hand.

This is a promising finesse bluff that appears identical to a double bluff.

[springiest]

Alice clues David’s red 4 with the rank clue 4.
Then Bob plays the red 1 from the finesse position.
Cathy plays the yellow 1 from the finesse position.

David would assume his 4 might be black.

why would he assume that? if it was k4, then cathy would not have blind-played anything because k4 is a valid single bluff target (as it is one-from-playable).
the only info he can have about his 4 is that it is NOT black or yellow.

[Jellby]

Because if Bob plays 1r and Cathy doesn't play, David will bomb looking for 2r and 3r.
If Cathy doesn't play and David thinks it's 4k and doesn't play, Bob might bomb next round looking for 2r and 3r (even if the 4 wasn't red, because why else would no one play?)

[Kaznaka]

I think Mimer is asking a question about double bluff.

For example, in the first turn:
Alice clues David’s red 4 with the rank clue 4.
Then Bob plays the red 1 from the finesse position.
Cathy plays the yellow 1 from the finesse position.

David would assume his 4 might be black.
However, David sees Cathy holds a red 3 in her second slot, right behind the yellow 1 she just played.
He then realizes his 4 can also be red, since this play confirms someone has a red 3 in hand.

This is a promising finesse bluff that appears identical to a double bluff.

I think in your example Alice can also color the red 4 to get red 1 and yellow 1 to play. The question is, does this have to promise that red 3 is in Cathy's hand? If it does, it reduces the opportunities for double bluffs. I tend to agree with Mimer that it shouldn't have to promise red 3. When two blind plays that don't connect occurred without a gap, bluff is revealed and nothing more.

[springiest]

Because if Bob plays 1r and Cathy doesn't play, David will bomb looking for 2r and 3r.
If Cathy doesn't play and David thinks it's 4k and doesn't play, Bob might bomb next round looking for 2r and 3r (even if the 4 wasn't red, because why else would no one play?)

this is wrong. if donald has k4, bob should play a single card and thats it - the bluff is fully resolved. k4 is the only one-from-playable 4 on the first turn, so donald knows he cannot have any other 4.
if it is NOT k4, cathy (or bob) should play more cards to make it either a true finesse or a Double Bluff.

and i agree with kaznaka that such a clue does not necessarily mean that anyone has a r3 (or any other card, for that matter).

[Jellby]

this is wrong. if donald has k4, bob should play a single card and thats it - the bluff is fully resolved.

Donald? Who's Donald? Please note there are no trumps in Hanabi

The problem is David doesn't know he has 4k. He only knows he has a 4, and 1r was played in response. He could assume it's 4k, but he could as well (and it could be argued preferably) assume it's 4r and search for 2r and 3r.

[springiest]

true, it is possible that donald has r2/r3 on finesse position and his 4 is really r4. but this assumption goes against Occam's Razor, especially given that there is a much simpler explanation that he just has k4.
since k4 is one-from-playable, it is a valid bluff target. and since r1 does not connect to a 4, the clue should be interpreted as a bluff rather than a finesse.

however, if the team was playing WITHOUT black powder, then this clue should get more than one blind-play! this is because no 4 is a valid bluff target on the first turn. but later in the game, depending on what cards are already played, it can be a single bluff again!

[Blacktango]

IMO a long finesse should always be the simplest explanation rather than a bluff.
Otherwise, you can't perform long finesses anymore, or you allow multiple answers to the same clue, which is bad.

Even if you disallow bluffs in situations where the clue can be interpreted as a long finesse, bluffs are still powerful and can be used in many ways.
On BGA, long finesses are quite powerful, so disallowing them makes us weaker.