Engine and Evaluation - czbar/ChessForge GitHub Wiki

Engine

The distribution package of Chess Forge by default installs the Stockfish engine. If desired, the user can connect Chess Forge to another engine.

Activating the Engine

In Study, Games and Exercises views, you can turn on the engine analysis by clicking the Engine On/Off toggle (red below).

 

The engine returns a number of top lines for the side on the move (green above) as specified in Engine Options dialog (green below). It also displays the Evaluation Bar (dark blue above), a visual representation of the position's evaluation. In the corner of the side with an advantage, the numeric representation of the evaluation rounded to one decimal place is also shown (light blue above). In our example, Black is on the move and the best continuation results in -0.48 (slight advantage for Black) so the system displays 0.5 on the top of the evaluation bar (representing Black's side).

 

Select Engine Lines to Paste Dialog

You can copy the engine lines into study, game or exercise. Select the relevant position (red below) and right-click over the Engine Lines window (green below) to open the Select Engine Lines to Paste dialog box (blue below). Alternatively, you can use the Tools menu and select the Paste Engine Lines option.

 

Select the lines you want to copy using the tick boxes on the left-hand side (purple above), then press the OK button (orange above) The lines will be pasted (added as variation) to the view (green below). Each line will be prefixed with the name of the engine that is being used.

 

Note that a double click, instead of a right-click will immediately paste the top engine line, skipping the line selection dialog.

Evaluation

In Study, Games or Exercise views (red below), you can use the Evaluation function to populate the Ev columns in the corresponding Scoresheet. The function can be applied to a specific position, an entire line, or multiple games, and it can also detect and flag bad moves.

Running Evaluation

Evaluate Position

This function evaluates the current position. Select the desired position (red below), open the right-click context menu to choose Evaluate Position (green below):

 

The system populates the Ev column in the Scoresheet for the current move (green below):

Evaluate Line

This function evaluates the entire line starting from the current position. Select the desired position (red below), open the right-click context menu to choose Evaluate Line (blue below):

 

The system populates the Ev column for all moves starting from the current one (blue below):

 

Evaluate Games

This function evaluates the main line of the selected games. To run it, open the Chapter menu (red below) and select the Evaluate Games function (green below):

 

Select the games you want to evaluate using the tick boxes on the left-hand side. You can use the Workbook tick box to evaluate all games in a workbook (blue below), the Chapter tick box to evaluate all games in a chapter (green below), or an individual game tick box to evaluate a specific game (red below). In the example below, Game 1 and Game 3 of the first chapter are selected for evaluation (red below):

 

System displays a progress bar:

 

The Scoresheet before the function was run (blue below) and after (green below) with updated the Ev columns for Game 1 and 3 (red below):

Bad Move Detection

In Game view only, if any evaluated move in the main line significantly worsens the position for the side to move, the system will flag it as a mistake ? or blunder using ?? (red below), and indicate the best move in that position (green below):

 

The thresholds for bad moves are set up in the View menu under Bad Move Detection option (red below):

 

Populate the relevant options:

  • Blunder (green above):

    • Evaluation Drop - the threshold for an evaluation drop. If the Evaluation Drop is set to 200, any move with a drop of over 200 centipawns will be flagged as a blunder. For example, if Black is to move and the evaluation changes from +2 to +4.01 after their move, that is a change of 201 centipawns and consequently will be marked as a blunder
    • No Detection Beyond - the threshold of the evaluation level, beyond which blunders are not flagged even if the Evaluation Drop is exceeded. For example, if the Evaluation Drop is set to 200 and the detection threshold to 300, a Black move that changes the position from -5 to -3.01 will not be marked as a blunder. This is because the evaluation dropped by 201 (beyond the Evaluation Drop of 200), but the position is still clearly won for Black since -3.01 is beyond the detection threshold of 300.

  • Mistake (blue above):

    • Evaluation Drop - the threshold for an evaluation drop. If the Evaluation Drop is set to 100, any move with a drop of over 100 centipawns will be flagged as a mistake. For example, if Black is to move and the evaluation changes from +2 to +3.51 after their move, that is a change of 151 centipawns and consequently will be marked as a mistake
    • No Detection Beyond - the threshold of the evaluation level, beyond which mistakes are not flagged even if the Evaluation Drop is exceeded. For example, if the Evaluation Drop is set to 100 and the detection threshold to 250, a Black move that changes the position from -3.5 to -2.51 will not be marked as a mistake. This is because the evaluation dropped by 101 (beyond the Evaluation Drop of 100), but the position is still clearly better for Black since -2.51 is beyond the detection threshold of 250.

Do Not Update Position Evaluation

In some cases, you may want to run the engine (red below) without updating the Ev columns. For example, a game may already have Ev columns populated after detailed, time-consuming analysis (blue below). You may still want to run the engine to see its suggested moves, some of which may not be included in the game lines. In such cases, use the right-click context menu to enable Do Not Update Position Evaluation (green below), and only then start the engine:

Deleting Evaluation

To delete evaluations run Clean Lines and Annotations function (red below):

 

Populate the required options:

  • Items to Delete - select the item you want to clean. Items relating to evaluations are Engine Evaluation and Bad Move Detection. In our example, we choose Engine Evaluations (green below).

  • Scope - to delete evaluations in the study, game, or exercise you are currently working on, select Current View. To delete evaluations in the current chapter or in the entire workbook, select the corresponding option (blue below)

  • Views to Apply to - select whether you want to delete evaluations in studies, games, or exercises (purple below). Note that when the scope is set to Current View, the available options under Views to Apply to will include only the view you are currently working on (e.g., only Study, only Game, or only Exercise)

 

The system will delete all relevant evaluations in the selected Scope and View. In our example, both Ev columns were populated (green above) and now the columns are empty (green arrows below)