[Retros] Variables

Rol, Guus G.A.Rol at umcutrecht.nl
Mon Nov 24 06:45:14 EST 2008

That is certainly an interesting variation, "Variable Pieces". I am willing to drop the V(ao) in favor of the V(ariable) :-)

I haven't read the original article so I can't be sure of the role it assigns to the à posteriori attribute, but going by the examples I suspect that the AP-qualification is misused here. The role adaptation of the Variable is actually an exquisite example of Post (F)actum logic.

Not attempting a full exposé of AP-logic here, I will just mention two essential characteristics of AP-logic that are missing:

(1) All AP-logic contains "justification by proxy", as in "parental guidance" implying "we don't trust the kid, unless accompanied by a parent (the proxy)". In chess: "we don't trust the e.p.-right, except when implied and validated by the manifested castling-right". There is no proxy in the resolution of the Variable role.

(2) Since the proxy operates independent of the AP-initiator (the e.p. move) there is always the possibility that à posteriori justification through the proxy does not take place. At this point the whole variation becomes "virtual", effectively non-existent. This option is not present when resolving the Variable pieces

Why the "Variable-logic" can be categorized as "Post (F)actum logic" is another story that warrants a longer analysis. At this point I will only note that the move Kh1-g1 in the paragraph "In diagram A, 1. Vb2-b6 Kh1-g1 is a legal sequence; White's move proves that the variable is a queen or a rook, black's move proves it's a rook" plays the same role as the move "black 0-0" would be play in a mutually-exclusieve post factum problem where it eliminates white's castling right.

Guus Rol

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