Chess -

By Eliot Slater -

"Statistics for the chess computer and the factor of mobility" -
IRE Transactions on Information Theory, 1950

...
To summarize the effect of these arguments it does seem possible
that a chess computer, which was programmed, beyond immediate
tactical tasks, to maximize the mobility difference between
itself and its opponent over a series of moves, might play a
strategically tolerable game of chess.

The mobility factor by itself might be a sufficient measure of
all the factors (rook on open file, etc) listed by Claude Shannon
as requiring evaluation under his headings 3 and 5. Moreover the
concept of mobility overlaps with other concepts much used by
chess players.

Control of space, when defined as the number of squares in the
opponents half of the board whose use can be denied him for at
least one move, proves to be correlated with mobility by a
coefficient of +0.83, i.e., the two concepts are nearly
identical.

"Development" is largely tantamount to the acquisition of
increased mobility for all the pieces together and for each piece
separately.

"Initiative" is nearly always in the hands of the player with the
advantage in mobility, and "having the attack" seems to consist
in having the opportunity for its aggressive application.

"Combination" though nowhere very precisely defined by chess
authors, seems to be the same thing as the exchange of one sort
of advantage for another, e.g., when superior mobility enables a
rapid concentration of attack on a piece which cannot be so
quickly defended, or when a sacrifice in material buys an open
file bearing on the opposing King.

The speculation may be offered that many other games, from
draughts to war, may be found by appropriate analysis to involve
the same concept, i.e., that advantage lies in creating a
difference in mobility. For the more restricted problem of
programming a chess computer however, these preliminary
investigations also suggest that a DIGITAL COMPUTER MAY PROVE AN
INNEFFICIENT INSTRUMENT, and that an analogue machine, or a
combination of digital and analogue machines, will provide better
results. [Capitals added by GFU]

Ref: Claude Shannon, "Programming a computer for playing Chess,
Philosophical Magazine, 41, PP 256-275 (1950)

***
This voltage can increase without limit as the beam length
increases without limit
.... Hermann Berth