I re-read the book quote, and nowhere in it does it define the terms "lookahead" or "pure tactics" that you have used.
It sounds to me like the authors (nearly 40 years ago) were talking about the general process of calculation. At least that's how I read it.
I'm not trolling you. I'm really trying to understand your point but I still don't get the key terms you are using. I have read a lot of books but have never heard those terms used before, so I'm trying to understand what you mean.
The book said: "It may seem surprising, but chess is not so much a game of deep thinkers as one of skilled perceivers." Substitute "distant lookahead" for "deep thinking" and "pattern recognizer" for "skilled perceiver" and you get the same intent I mentioned. The book is saying that lookahead ability seems not to be the key ability that makes a chessplayer good, but rather memory of similar patterns.
The practical application is evidenced in one of the most frequent FAQs you see posted in new threads here all the time: "How do I get better at tactics?" The current default advice amounts to "Here, kid. Read this chess puzzle book and you'll somehow get better." But some of those people don't get better, or if they do get better they often don't recognize when such a position arises in a game they're playing, or they might encounter a situation that doesn't match any pattern they've seen before, or they might encounter a need to look ahead farther than the usual 3-5 moves in puzzles, or they might fail because the tree was too thick, or whatever.
Computers haven't essentially changed since that book was published. Many people don't seem to understand that. All that has really happened since then is that computers have gotten faster, so they do the same stupid things they did in the '70s, only a lot faster. The terms I'm using are largely from computer science, which is my background.
http://www.chess.com/forum/view/general/how-computer-works-in-playing-chess
----------
(p. 6)
What about those com-
binations that missed their mark entirely or even boomeranged owing to a
hidden zwischenzug tactic or just an obvious defensive resource? Why
weren't they included in Fred Reinfeld's book? Even worse, I felt that a
reader of such books could hardly benefit in actual practice. After all, Fred
wouldn't be there to tap me on my shoulders during a championship game
and whisper to me, "Now Yasser. Now you can sacrifice a piece for a win-
ning combination!" It seemed to me that I'd more often miss a combina-
tion than not.
Seirawan, Yasser. 2006. Winning Chess Combinations. London: Gloucester Publishers plc.
----------
(p. 14)
Shannon's type-A strategy has some serious weaknesses. First, one can-
not examine even a moderately deep tree in a practical amount of time. In a
typical chess position there are around 30 to 35 legal moves. If one were to
use the type-A strategy with a 4-ply lookahead, there would be about
1,000,000 terminal positions that must be scored and about 30,000 non-
terminal positions at which all legal moves must be generated. If one as-
sumes a position can be scored in 10 microsec and that a move generation
requires 1 msec (these figures are well less than one-tenth the amount
of time required by most current chess programs!), then a move would
require 40 sec. The type-A strategy with a 6-ply look-ahead would con-
sume about 1000 x 40 sec or about 1 hours per move! Thus it is clearly
impossible to look ahead more than four ply.
Newborn, Monroe. 1975. Computer Chess. New York: Academic Press.
Many of your world champs and your regular grandmasters excelled in Math.
Really? Sounds like BS to me.
I can name maybe 1 GM who "excelled in Math" John Nunn.
Ok, now you name... 5 world champs for me. Ok Maybe Lasker and Euwe... Botvinnik I think would be a stretch. That's 2.5