#Running an analysis
When a match ends, press Analyze in the match list, or use the analysis controls on the board. The engine replays every decision of the match, works out what the best play was, and records what each actual play cost against it.
#On this device or on our servers
The run modal asks that first, because the answer decides everything below it.
On this device uses the same WebAssembly engine you play against. It is free, needs no account, and the match never leaves the browser. It is bounded by what the device can do: a whole-match pass runs up to 3-ply here, and rollouts are not available at all, the browser engine having no rollout path.
On our servers runs the same analysis on our hardware, against models we do not publish for download, at depths a browser cannot reach. It needs an account, and how much of it you get is what a plan changes. See Accounts and plans.
#How deep
| Depth | What it does |
|---|---|
| 2-ply | A first pass. Catches blunders, not subtleties. |
| 3-ply | What the error-rate bands and the study pages are calibrated on. |
| 4-ply Standard | One further level of opponent reply. Around twenty times the cost. |
| + rollout Standard | Plays each move out 360 times instead of searching it. |
| ++ rollout Standard | 720 games per move, played deeper. The strongest answer available. |
3-ply is the one to reach for. Below it the numbers move under you; above it the cost grows much faster than the accuracy does, which is why the deeper rungs are better spent on a handful of positions than on two hundred of them.
Whole-match passes default to 2-ply and a single position to 3-ply, both adjustable in Settings and from the strength menu on the analysis itself.
#Analysing part of a match
A run does not have to cover everything. Beside the whole match you can re-run only the moves already flagged as errors, everything from the move you are looking at onwards, or the decisions that were close enough for the depth to matter. Re-running a narrow scope deeper is usually a better use of a rollout than deepening the whole match.
#Importing a match
Press Import Match and load one of:
| Extension | Program |
|---|---|
.mat |
JellyFish, and the interchange format most programs read |
.xg |
eXtreme Gammon |
.bgf |
BGBlitz |
.sgf |
GNU Backgammon |
The last three carry that program's own analysis, so an imported match opens with its evaluations already attached and you can compare them against ours before running anything.
A .mat import is kept in this browser until you choose to save it to your
account. Where your matches are kept
explains why, and how to save one.
#Where your matches are kept
Without an account, every match lives in this browser only. Clearing site data, or playing in a private window, removes it, so export anything you want to keep.
Signed in, a match can also be saved on our servers, where no browser setting can remove it and any device you sign in on can open it. In Matches, the cloud icon on each row says which it is: a cloud with a tick is saved on the server, and a cloud with an arrow is in this browser only. Press the arrow to save that match.
Some matches are saved for you and some wait for you to choose:
| How the match arrived | Saved to the server |
|---|---|
| A session against the engine | Automatically, when you end the session |
| A transcription | Each time you press Save |
An .xg, .bgf or .sgf import |
Automatically, as it imports |
A .mat import |
Only when you press its cloud icon |
A .mat import is left to you on purpose. A free account holds a limited
number of saved matches, and loading a folder of old .mat files should not
fill those slots without asking. That is also why a transcription can bring up
a saving prompt that an import does not: see the next section. A match that
could not reach the server because you were offline is saved as soon as the
connection comes back.
#When your saved matches are full
A free account shows how many saved matches it is using at the top of Matches, and the plans page lists how many it holds. Saving one more once they are full opens a prompt that names your oldest saved match:
- Free up a slot & save moves that oldest match to Deleted matches and saves the new one in its place
- Not now leaves the new match in this browser only, where you can save it later from its cloud icon
Nothing is destroyed. A match moved out this way keeps its analysis, can be put back from Deleted matches at any time, and returns by itself if you upgrade. While it is out, its share link stops working. Ordering a server analysis needs a copy of the match on the server, so it can bring up the same prompt. Standard and Pro hold unlimited saved matches.
#Exporting a match
Export Match in the sidebar downloads the current or completed match as a
.mat file, which GNU Backgammon, eXtreme Gammon and other backgammon software
read. Matches with a HedgeHog analysis attached can also be kept in the OGXM
format, which stores the moves and the analysis together.