Two halves. The first three sections are the words the game uses, which you will meet in a book, at a club and in the explanations HedgeHog writes about a move. The last three are the vocabulary the app itself names positions with, and they are drawn from the same list the Study flow chart and the tags beside an explanation are drawn from, so they cannot say anything different here.
Equity, the error symbols and the accuracy ratings are numbers rather than words, and they have their own page: see Reading the analysis.
#The board and the checkers
#Anchor
A point in your opponent's half of the board that you hold with two or more checkers, so it cannot be hit or taken from you. An advanced anchor is on their bar point or their 6, 5 or 4 point, and it is the useful kind: it stands in the way of their checkers and gives yours somewhere safe to wait. A deep anchor, on their 3, 2 or 1 point, is just as safe and blocks almost nothing, which is why it usually ends up saving a gammon rather than winning a game.
#Attacker
A checker of yours aimed at hitting: a blot or a spare within six pips of an opponent's blot, of a point of theirs that will soon have to be broken, or of an open point in your home board where a checker of theirs on the bar can come in. The same checker is often a builder as well. As a builder it aims at a point you want to make; as an attacker it aims at a checker you want to hit.
#Bar
The ridge down the middle of the board. A checker that has been hit goes there, and until you re-enter it in your opponent's home board you may not move anything else.
#Bar point
Your 7 point, the one just outside your home board. It is the point that turns a five-point blockade into a six-point one, which is why it is worth more than its position suggests.
#Blot
A point held by a single checker, which can therefore be hit. Leaving one is often right: the question is never whether a blot is safe but what being hit would cost against what the blot buys.
#Builder
A spare checker close enough to a point you want to make that it could help make it next roll. Counting builders is how you compare two plays that both look quiet.
#Crossover
One checker moving from one quadrant of the board into the next. Counting the crossovers each side still owes is a quick way to see who is ahead in bringing their checkers home, without counting pips.
#Direct and indirect shots
A direct shot is six pips away or fewer, so a single die can hit it. An indirect shot needs two dice to combine, and is much less likely: of the thirty-six rolls, eleven hit a direct 6 and only six hit an indirect 8.
#Golden point
Your 5 point. It is the best point on the board to make early: it blocks the opponent's back checkers at the place they most want to go, and it is the anchor they most want for themselves.
#Home board
The last six points before your bearing-off tray, where every checker has to arrive before you can start taking them off. The six points beyond it are the outer board, and a checker on the bar re-enters in the opponent's home board.
#Pip count
How many pips you would have to roll to bring every checker home and bear them all off. It is the score in a race: the side with fewer pips is ahead, and by how much decides whether a double is a cash, a take or a pass.
#Prime
A run of consecutive points you own, in front of a checker of your opponent's. Four or five of them are hard to escape; six in a row cannot be jumped by any die at all, so a checker behind a six-prime stays there until you are forced to break it.
#Return shot
The shot your own hit hands back. Hitting nearly always leaves something, and a play that hits is being compared with a play that does not on what comes back as much as on what it gains.
#Slot
Leaving a single checker on a point on purpose, meaning to cover it next roll and make the point. It risks a hit now to make a valuable point sooner.
#Spare
A checker on a point you already own, beyond the two that hold it. Spares are what you have to play with: a position with none has to break something every roll, which is the shape behind most timing problems.
#Words about a plan
#Diversification
Arranging your own checkers so that different numbers each do something useful, rather than several numbers all doing the same job. It is the mirror image of duplication, aimed at your own dice instead of your opponent's.
#Duplication
Leaving your opponent in a position where one number has two jobs at once, so that the roll which hits you is also the roll they need for something else. It is the cheapest kind of safety, because it costs nothing to arrange.
#Tempo
Hitting for the roll it costs your opponent rather than for the contact. A checker on the bar has to come in before it can do anything, so a hit that is not otherwise attractive can still be the play when it stops a plan of theirs one roll short.
#Timing
Whether you can hold a plan together long enough for it to pay off. A back game or a holding game needs spare pips to burn while you wait; run out of them and you have to break the very points you were waiting behind.
#Wastage
Pips you can no longer use. Bearing a checker off the 3 point with a 6 wastes three of them, and a stack far back in a race will waste more before it gets home. Two sides with the same pip count are not equal if one of them is going to waste twice as much.
#Words about the cube
How the app puts a cube decision on screen, and what the match score does to the answer, is in The cube.
#Cash
Doubling in order to be passed, and collecting the point on the table. Cashing is right when you are far enough ahead that the opponent cannot take, but not so far ahead that playing on for a gammon is worth more.
#Crawford rule
In a match, the first game after either player reaches match point is played with no cube. It stops the trailer from doubling immediately with nothing to lose, and HedgeHog applies it to every points match on its own.
#Doubling window
The band of winning chances in which doubling is right and the opponent still has a take. Below it you gain nothing by doubling; above it they pass and you have cashed a game you might have won more from.
#Jacoby rule
A money-game rule about when gammons start counting. What the setting does, and when it applies, is in Settings.
#Market losers
The sequences of rolls after which your opponent would no longer have a take. They are what tells a double you can wait on from one you cannot: if enough sequences would carry the position past their take point, waiting means often being left with nothing to offer that anybody would accept. They are counted as sequences rather than single rolls because the next chance to double is two rolls away, not one.
#Match equity
Your chance of winning the whole match from the current score, which the app shows as MWC. In a match that is the real currency: a play or a cube action is right when it maximises match-winning chances, and at some scores that is a different answer from the one money play would give.
#Pass and take
The two answers to a double. Take accepts it, doubling the stake and handing you the cube; pass declines it and concedes the current stake. Passing is never a disaster on its own, and taking a game you should have passed is one of the most expensive mistakes available.
#Take point
The share of the games you need to win from here for taking to be better than passing. Comparing your actual chances against it is the whole of a take decision.
#Who owns the cube
At the start of a game the cube belongs to nobody and either player may double. After a take it belongs to the player who took, and only they may double next. Owning the cube is worth real equity, which is why a double that gives it away cheaply is a mistake even when the position is good.
#Position classes
HedgeHog names the kind of position you are in, on the tags beside a move explanation and on the Study flow chart. These are the names, in the order a game meets them.
| Term | What it means |
|---|---|
| Contact | Each side still has a checker behind one of the opponent's, so hits are possible, and nothing more specific applies: no prime, no anchor, nobody on the bar against a made board. Every game starts here, and a game comes back here whenever a plan collapses. It turns into whichever of the stage-1 plans forms first, or straight into a race once the last checker gets past. |
| Blitz | The opponent has a checker on the bar and you have made three or more points in your home board, so their entering numbers are limited and every roll of yours can point on them again. The plan is to make more home points and win by containment, often with a gammon. It becomes a closeout when all six points are made, and it falls back to contact or a priming game once the opponent enters and anchors. |
| Backgame | You hold two or more points in the opponent's home board while the opponent holds a prime of four points or more. You are usually well behind in the race, so the plan is not to win it: hold the points, let the opponent run out of safe moves, and hit a shot as their last checkers come home. It turns into a win from nowhere when the shot lands, and into a gammon save or a lost gammon when it never comes. |
| Prime vs prime | Both sides own a prime of four points or more, and each has a checker stuck behind the other's. Neither can move the trapped checker, so the game turns on timing: whoever runs out of spare moves and has to break first usually loses the checkers they were holding back. It resolves into a blitz, a closeout or a race for whichever prime holds together, and this class is always shown as belonging to both sides. |
| Prime | You hold four or more points close together, with at most one gap between them, and at least one of the opponent's checkers is behind the blockade. The plan is to keep it intact while the rest of your checkers come around, and to extend it toward a full six-prime. It turns into a blitz or a closeout when you attack the trapped checker, and into a race when the checker escapes or you are forced to break. |
| Mutual holding | Both sides hold an advanced anchor: the opponent's bar, 6, 5 or 4 point. Neither side can be attacked and neither wants to break first, so the position is a race with two ambushes in it. It is decided by who has to leave a shot as the checkers come home, and it turns into a plain race when both anchors break cleanly or into an attacking game for whoever hits. |
| Holding | You hold an advanced anchor, the opponent's bar, 6, 5 or 4 point, and the opponent holds no such anchor of their own. The anchor cannot be attacked, so the plan is to sit on it while they bring their checkers home, take the shot if one appears, and run for the race if it does not. It turns into a race when you break and run, and into an attacking game for either side after a hit. |
| Ace point | You are anchored on the opponent's 1 point while they have three or more blocking points in front of you. It is the safest anchor and the least useful one: it blocks nothing, wins few races, and is very hard to lose a gammon from. It usually turns into a gammon save with one last shot at the end, and only rarely into a win. |
| Deuce point | You are anchored on the opponent's 2 point while they have three or more blocking points in front of you. One point further out than the ace point, which is enough to matter: a checker hit from here has further to travel home, and the anchor is a usable base to build in front of. It turns into a gammon save when no shot comes, and into a real game when one does. |
| Butterfly | You are anchored on the opponent's 3 point while they have three or more blocking points in front of you. The most useful of the three deep anchors: a checker hit from here has the furthest to come home, so a late shot often wins the game outright rather than merely saving the gammon. It turns into a holding game when you advance the anchor, and into a gammon save when the shot never arrives. |
| Anchor | The umbrella class for a deep anchor: exactly one side holds the opponent's 1, 2 or 3 point while that opponent has three or more blocking points in front of it. When the chart knows which of the three it is, it names it instead (ace point, deuce point, butterfly). The plan is the same in all three: stay safe, save the gammon, and hit a shot as the last enemy checkers come home. |
| Closeout | You have made all six points of your home board and the opponent has a checker on the bar, so they cannot move at all until you are forced to open a point. A closeout is always also a blitz, since a blitz is what took the six points. The plan is to bring the rest of your checkers home safely and then choose between cashing and playing on for the gammon. It turns into a bearoff, into a gammon save for the opponent, and back into contact if the board has to break too early. |
| Race | The rearmost checkers have passed each other, so no checker can ever be hit again and the pip count decides the game. The plan is pure efficiency: fill the home board and waste as few pips as possible bearing in. It leads only to a bearoff, to a gammon save for whoever is behind, or straight to an outcome. |
| Gammon save | One side has every checker in its home board while the other does not. The class belongs to the side at risk, the one racing to take a checker off before the opponent finishes, not to the side bearing off. The plan there is speed over safety, since a wasted roll is a whole extra point. When the trailing side still has a checker on the bar or in the opponent's home board, the same class covers saving the backgammon. |
| Bearoff | Both sides have every checker in their own home board. Nothing can be hit, so the game is a pure bearoff race and what decides it is how few rolls each side wastes. It leads straight to an outcome, and to a gammon only where one side has not yet taken a checker off. |
| Last roll | Neither side has more than eight checkers left, and neither has more than 24 pips to go, so the game is down to its final rolls. Whether the side on roll finishes in the rolls remaining is now a countable question rather than a judgement, and the cube is dead: a double here is a cash or nothing. It is the last stage before an outcome. |
#Cube verdicts
What the engine says the cube action is.
| Term | What it means |
|---|---|
| No double | The position is not yet strong enough to hand the cube over. A double would be taken, and the cube you gave away is worth more than the equity the double buys. The plan is to play on and offer it once the position has improved or become volatile enough that waiting risks losing the chance. |
| Double, take | You should double and the opponent should accept. The doubling window is genuinely open on both sides: you are far enough ahead that playing on at the current cube wastes equity, and the opponent is not far enough behind to be better off conceding the point. Both failing to double and passing would cost equity here. |
| Double, pass | You should double, and the opponent is past their take point: accepting would lose more on average than giving up one point at the current cube. This is the cash. Missing it is among the most expensive cube errors there is, because a single roll can turn the point on offer back into a game. |
| Too good to double | You are so far ahead that doubling would be a mistake in the other direction: the opponent would pass, you would collect one point, and the gammons and backgammons you were on course for would be thrown away. The plan is to keep the cube where it is and play on for the gammon, then double later only if the position starts to slip. |
#How a game ends
Six outcomes, worth one, two or three points. What the cube is on multiplies them.
| Term | What it means |
|---|---|
| Win backgammon | Three points: the opponent bore nothing off and still had a checker on the bar or in your home board. |
| Win gammon | Two points: the opponent did not take a single checker off. |
| Win single | One point: the opponent got at least one checker off before you finished. |
| Lose single | One point against you, with at least one of your checkers borne off. |
| Lose gammon | Two points against you: you did not take a single checker off. |
| Lose backgammon | Three points against you: nothing borne off, and a checker still on the bar or in the opponent's home board. |