Value

When discussing go or CGT (Combinatorial Game Theory), the term “value” is used in many different senses. Use the links below to see the details:

• The “value” of a position:
  • The count: An estimate of the expected contribution of some region of the board to the final score.
• The “value” of a single move:
  • The gain is the number of points by which it shifts the count in favour of the player making it.
  • In CGT, the incentive is the difference game – in favour of the player making the move – between the game in which the move is made and the option to which they move; this is effectively the gain calculated as an abstract game.
• The “value” of moving first in a position:
  • The move value: the value of playing first in a position, as opposed to allowing the other player to do so. This is calculated by comparing the results after sequences started by Black and White.
    • There are two main approaches to calculating this, either of which may be intended in a given context:
      • Deiri counting (The older method) – The move value is regarded as the swing, i.e. the difference in count between the positions after a black and a white play.
      • Miai counting (Preferred in modern endgame theory) – The move value is regarded as the swing divided by the local tally
    • The value of a threat: the move value of the position created by the threat, i.e. the cost of allowing a follow-up move when the threat is ignored rather than answered.
• Other concepts — these should be added here!

See also

• Counting – Techniques for evaluating positions and games
• Counting without tears – (under construction)

Discussion

Patrick Traill: I have not found a page with this sense of “value”, to which Bill Spight’s never completed article Counting without Tears refers, so I have made this as a place-holder. It is of course close to counting, but that does not actually talk of the value of a move. Either that or this could be extended.

Robert Jasiek: The page alias "Value" is totally improper because there are very many values in go theory, of which most are not 'values of moves'.

Patrick Traill: I suppose you mean the alias “Value of a Move”; given that you have clarified the distinction between move value and gain, I feel that that alias is now fairly appropriate, though it may still be worth making it an article in its own right (with alias Move Value, or vice versa), and reducing this to something more like a disambiguation page.

Robert Jasiek: I do mean Value for the reason stated.

PJT: So do you mean that the name (not alias) of this page is inappropriate? What would you like to see instead?

Robert Jasiek: I did not know that a page name is not an alias; so if Values is the page name, I mean it. Since there is an alias Values of a Move, I thought that this page was meant to be about values of a move. Now you have made it a page of all values. If so, the alias is wrong. If so, you must abandon your prejudice that values of a move, counts and CGT numbers would be the only values because there are many other values you do not know. Mathematical Go Endgames is not the only source of go theory...! Some other pages refer to values of a move so there must be a page with the title Values of a Move. Another page with eventually all values can also exist and then with the title Values. A third page might be about only the CGT values. But do not try to let one page be three pages simultaneously!

PJT: Perhaps you were confused by following a link to the alias Value of a Move (I thought I had in such a case seen a page with the alias displayed as title! – but I could not reproduce that). The title of this page is Value (singular), and the alias Value of a Move is also singular. You seem to be agreeing with me about the ideal organisation, but I think this is a useful start. I hope you will take the opportunity (when you are not too busy!) to add terse summaries of other concepts of value to this page, linking them (where possible) to appropriate articles.

Robert Jasiek: "value" itself is not a term! I do not have have time. You might cite from my books and other sources.

PJT: “Value” may not be a technical term in your usage, but it satisfies the definition A word or phrase, especially one from a specialised area of knowledge. given at Wiktionary.