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Turbo Chop For Two Player Hanabi

Introduction

Referential Sieve (RS) has a property: certain cards are never on chop. This means they never get to discard for free, it will always take (part of) a clue. On the other hand, these cards do not have to be clued to be saved. The quality of these "not sieved" (ns'd) vs "sieved" (cm'd) cards (that were on chop) has a significant impact on the game in ways that the players can only minimally control. When giving loaded clues, RS players commit to not sieving the top previosly-sievable card(s) in the deck whose identity they do not yet know.

A Turbo chop system does not let any cards pass through the sieve for free forever. So, we no longer have the advantages or disadvantages of cards being let in through the sieve permanently. Compared to referential sieve, this turbo chop system has some advantages:

  • It matters less whether ptd is given on a specific turn:
    • Only conventional plays can change which card is the chop.
    • If ptd being given is unclear (if it is hard to know if a taken action was common knowledge) and we want to give ptd, we can simply give ptd again, since the chop hasn't changed.
  • We have less redundancy in the types of signals we give, since trash pushes now refer rightward and bias plays towards chop.
    • This comes from the original justification of a trash push as an anti-discard clue, however it might be better to think of a trash push as a bad touch-avoiding play clue and so keep its left-referring meaning meaning. (12/21 edit: I tend to think this is good and so no longer stand by refer-right TPs)
  • Later chop-moves are treated as slightly more important cards to hold on to than early chop-moves. For exmple, we are less punished for cm'ing a noncritical 4 then having to find a way to save a critical 4 - a referential discard clue may work, whereas it would not (or would require contextual reads) in traditional RS.
  • Less lowroll potential for quality of ns'd cards.
  • Free choice between different clue signals can impact which card is next on chop, allowing us to get two safe actions for one clue more often.
  • The value of giving a clue depends less on the identity of the next "potential chop" card in the deck, but rather on a chop card the clue-giver can see. This allows players to make more informed decisions about when to give clues.
  • Not-(yet-)sieved and chop-moved cards are sorted, with the chop in the middle. This makes playing high-effort games (eg contagious ptd) easier.

Turbo chop has these lateral differences:

  • Cards can only be temporary not sieved; all cards will eventually have to be chop-moved for them to stay in hand for the long haul.

Turbo chop has these disadvantages:

  • Less highroll potential for quality of ns'd cards.
  • We cannot always tell chop to play, prioritizing slot 1 instead. Some play signals look immediately necessary. These facts combine to mean not every safe action given should move chop.
  • We have to keep track of chop-moves, limiting our ability to play very low effort games.
  • We have slightly more issues following good touch principle and expect fill-in discards more often.

Ambient Principles

Good touch principle

If a player's card is touched, they are to assume that it has an eventually-playable identity unique from other touched cards in their hand and known cards in their teammate's hand until either this is not possible anymore due to explicit or conventional information.

Good touch play order

Context dependent. TBD.

Chop

When not provided any other safe actions and not locked, players are given permission to discard their chop. Their chop is the rightmost untouched card not chop-moved.

Permission to discard

Once a card has permission to discard, that player is loaded by a discard. When a player has permission to discard or known trash, they start being able to receive information about their upcoming chop, albeit in a more limit capacity that when it is in danger.

Safe action principle

We design our conventions with the following ideas in mind:

  • We want Alice to be allowed to give a safe action to Bob any time he has one.
  • If chop is important, and play signals can wait, we let it discard.
    • If Alice gives a play signal, and it does not appear urgent, then she is declining (or delaying) the opportunity to tell Bob to discard his chop. With this justification, such a clue chop-moves Bob.
    • If Alice gives a play signal that does appear urgent, she may be worried about Bob's next safe action following a discard of his chop. Bob should not take this as telling him much: the team neither moves Bob's chop nor marks it as a safe discard.

Play and discard clues

Fill-in plays and discards (fixes)

Any time Bob has a touched card, Alice can provide its full identity by filling in its value (clue its rank if it has color info on it or vice versa). So that Alice can always give Bob a safe action whenever he has a touched actionable card, we say that fill-in clues provide no other safe actions. This is just like in Referential Sieve.

Fill-in play clues and early fix clues chop-move one card. Fix clues preventing the card from immediately bombing do not move chop.

NB: whether early fixes chop-move ought to be dependent on the requirements of the variant and perhaps the playstyle of the team. In easier variants we are more likely to want to fix early to sync up the team, meaning we are incentivised to not think of any fix clues as early and so not chop-move.

Referential play clues

Color clues provide play signals referring to the previously untouched card to the left of the focus (with wrapparound), biasing leftward in hand when multiple cards are newly-touched. This means slot 1 has highest referral priority and lowest focus priority. This is the same color play convention as in referential sieve

Referential play clues chop-move one card when not touching leftmost previously-untouched card in hand. If they touch the leftmost previously-untouched card in hand, they do not chop-move. This is due to the urgency principle.

Referential discard clues

Rank clues focus the rightmost newly-touched card not rightward of chop if any exist, and otherwise they focus the rightmost newly-touched card in hand.

Chop has lowest referral priorty, and seeming to refer to chop is a signal that Bob is locked: that is, he has no safe actions.

Referential discard clues chop-move all cards between the signaled card and chop if the signaled card was not-sieved. They chop-move all cards in hand if the signaled card was previously chop-moved.

Rank direct play clue

  • Like H-group. Chop focus, then leftmost.
  • 1s Chop-moves the whole hand, even in stalling situations.
  • Other clues chop-move once.

Trash pushes

When we want a card to play, but we would be bad touching to do so with a referential color play clue, very often a rank clue would by itself reveal trash.

Thus, if a rank clue reveals only trash, we think of it as an early fix of a referential play signal: the card to its left should play.

TODO: if referring left, touching one trash, and color was avaible, should a second card play after it discards? If so, what card?

Rank loaded play clues

When Bob is loaded, a rank clue to him is not interpreted as a discard clue. We chose for it be a play signal referring the opposite way of referential color clues work: they refer to the previously-untouched card rightward in hand, biased rightward in hand.

Rank loaded play clues do not chop-move any cards.

Reclues (Prompts, Bluffs, and Finesses)

A clue which does not newly touch cards, fills in at least one card, and is not a fill-in play or discard clue is either a promise that one of the filled-in cards is delayed-playable (prompt, finesse, both) through playing certain other cards in hand or that just the first untouched card in hand is playable (bluff).

When interpreting a reclue:

  1. If connecting plays could only involve touched cards, play touched potentially-connecting cards from the right until it is playable. It is a prompt. The clue contains no more clue meaning.
  2. Otherwise, blind play slot 1.
  3. If the blind play could connect immediately to a filled-in card, play said card. It is a finesse. The clue contains no more meaning.
  4. Otherwise, if the blind play could connect through touched cards, play those from the right. It is a finesse-into-prompt, then play the filled-in card. The clue contains no more meaning.
  5. Otherwise, it is a bluff. The clue contains no more meaning.

For reclues, bluffs and prompts chop-move one card. Finesses do not chop-move. (This is somewhat suspect! Maybe bluffs are valuable enough to not chop-move. Ditto for prompts newly-drawn cards can block them.)

No-info two card plays

Same as RS. Get two blind plays (double bluff) or one blind play and one touched card to play (no-info finesse) depending on the situation.

A no-info clues do not chop-move any cards.

Slot 1 direct play discard promise

A direct rank play clue to slot 1 that doesn't fill in any other info also asks slot 2 to discard. It does not chop-move(?).

Chop-moves for clue signals

  • The starting hand is not chop-moved.
  • 1s direct play clue chop-moves the whole hand.
  • Other rank direct play clues chop-move only one card.
  • Fill-in play clues chop-move one card.
  • Early fix clues chop-move one card, while timely fix clues chop-move no cards.
  • Discard clues chop-move all cards between discard and the chop. If a previously chop-moved card is told to discard, the whole hand is chop-moved.
  • Referential color play clues chop-move one card if the clue does not touch the leftmost previously-untouched card in hand.
  • Referential color play clues chop-move no cards if the clue toucheds the leftmost previously-untouched card in hand.
  • Trash pushes chop-move one card (only outside stalling situations).
  • Rank loaded play clues do not chop-move any cards.
  • No-info two-card plays do not chop-move.
  • Direct-play discard-promise clues chop-move one card.
  • Additionally, all touched non-kt is chop-moved.

If the chop card chop-moved by a signal is also a card told to play or is touched by that signal, that still counts as that signal's chop-move.

Reference Table

sadf asdf
asdf asdf asdf

Stalling situations

Generally speaking, play signals given by stalling players do not chop-move. They are urgent because the clue-giver would like to give a valuable clue. This is most relevant at the start of the game and in 8-clue states. An exception to this is giving 1s as a direct play. 1s still chop-moves the whole hand.

Starting hand stall

Rank touching slot 5 still. Maybe should be rank touching slot 1?

Locked hand stalls and the Unlock Promise

Same as RS

Special Moves

Sarcastic/Gentleman's discard

Same as RS. Maybe should look in cm'd cards, then cards from the left? Or maybe still from the right, but skipping chop? Maybe if it gets a card not touched or cm'd it should chop-move one card?

Bomb Lock