And White's strategy really is to strangle Black's position.

Three Rings for the Elven-kings under the sky,

Seven for the Dwarf-lords in their halls of stone,

Nine for Mortal Men, doomed to die,

One for the Dark Lord on his dark throne

In the Land of Mordor where the Shadows lie.

One Ring to rule them all,

One Ring to find them,

One Ring to bring them all and in the darkness bind them.

sorry, I'm more concerned with global warming, human trafficking, Chinese enslavement of minority races, stuff like that.

If I were to list books that had influenced people to be concerned about environmental degradation, Lord of the Rings would be in my top 10. It would probably be #1 in the fiction subcategory.

I read 'The Lord of the Rings' and it's predecessor, 'The Hobbit', as a teenager. They are amongst the most inventive books I've read (almost on a par with Douglas Adams) at least to start with.

I struggled with 'The Return of the King' though which seemed like one epic battle after another and I never finished it. It's staring at me right now from my bookcase opposite where I'm sat (right next to my Douglas Adams collection) so one day I might get round to completing it.>

Yes, very good pun.

IMHO, "The Lord of the Rings" trilogy is one of the greatest works of English literature of the 20th century.

Criticism from literary purists notwithstanding, Tolkien was able to create an amazingly vivid universe which transports the reader to another place—a world that feels every bit as real as the one we live in.

As for the motion pictures, director Peter Jackson did about as well as could be expected with the trilogy, albeit there were a few cases where the use of CGI was gratuitous (e.g. the scene from the Mines of Moria section of "The Fellowship of the Ring" which necessitated Aragorn's absurd "lean forward" line).

That's an interesting question and I'll try to answer it. I was (surprisingly?) able to locate, download, install, and analyze the position after 17.c4 with a version of Gandalf which I think is pretty similar, if not the same, version used in this game. So I'll be able to provide some quantitative data to back up my opinions.

First, some background information. The 26th Dutch Open Computer Chess (DOCC) 2006 tournament (https://www.chessprogramming.org/DO...) was held in Leiden from Nov 3 through Nov 5. Fifteen engines participated and each engine played 8 or 9 games depending on whether they had a bye or not. Rybka (presumably version 2.2 released in Oct-2006) won the tournament with a Fischer-like perfect score of 9.0/9 and Loop (presumably the 32-bit version, https://www.chessprogramming.org/Lo...) finished 2nd with a score of 7.0/9 (loss to Rybka + 2 draws). Gandalf finished 5th with a score of 5.0/9 (3 losses, 2 draws).

The time control was 90 minutes for the entire game. If we assume an aveerage of 40 moves per game (not necessarily a good assumption), then that averages about 2.25 minutes/move. This will help identify approximately how much time Gandalf had available to calculate its 17th move.

But back to your question. In response to your wondering why Black's silicon mind perhaps passed on 17...a4 it could be because it simply did not <consider> 17...a4 as Black's best move at the time it <played> 17...Rc8. Chess engines will play the move that they consider best up to the time that the engine time management function says its time to move

I had Gandalf analyze the position after 17.c4 using 2 threads (the maximum that this version of the engine supported), a 1.6 GB hash table (again, the maximum that this version of the engine supported), and supported by a 6-piece Nalimov tablebase as was available at the time the game was played. I let it calculate for about 6.5 hours and in that time it reached a search depth (d) = 23 ply, although I had the GUI set to display results only starting at d=8 (low ply evaluations are notoriously unreliable) so it only displayed the results of a 16 ply analysis. In those 6.5 hours it considered either 1...a4 or 1...Rc8 (as played in the game) ranked as either its #1 or #2 move 15 times. Furthermore, during those 15 times the average difference in its evaluation of these 2 moves was just [0.01], so it effectively considered either move to be as good a reply to 17.c4 as the other. This often happens in complex positions. An engine finds 2 moves that it considers to be equally good and in successive search plies the two moves alternate being ranked #1 or #2.

But it's even a little closer than that. In 11 of those times that 17...a4 and 17...Rc8 were ranked #1 or #2, in 11 (!) of those times the two moves had the <same exact> evaluation. Whenever that happens the engine lists the move that it first finds while traversing its search tree and therefore it gives that move its #1 ranking. So the fact that Gandalf ranked 17...Rc8 as #1 twice as often as it ranked 17...a4 #1 is mostly due to 17..a4's "bad luck" in being found in the search tree later than 17...Rc8.

But the above applies if Gandalf had about 6.5 hours available to determine which was its best reply to 17.c4. In reality, given the time control, it only had an average of 2.25 mins/move. In that time Gandalf was able to reach d=17 and only 10 evaluations were displayed. Of those 10 plies and if evaluations were not considered 17...a4 was never ranked ranked #1, 17...Rc8 was ranked #1 9 times. But the average difference in their evaluations from d=8 through d=17 was only [0..02], again effectively equal, and 17...a4 and 17...Rc8 had the same evaluation 7 of those 9 times (!). So <really> bad luck for 17...a4!

Maybe. But this was a game between 2 silicon units (I can't – yet? – call them silicon life forms!) and you did say that 17...a4 might have better chance in a game between 2 carbon life forms. The following position is reached after 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be3 e5 7.Nb3 Be6 8.f3 Be7 9.Qd2 O-O 10.O-O-O a5 11.Bb5

click for larger view

Opening Explorer has 77 games with this position (Opening Explorer). Fifty-nine (59) continued with 11...Na6 when White had a scoring % of 40.3% and Black a scoring % of 58.7% and only 8 games continued with 11...Nc6 as played in this game and White then had a scoring % of 56.3% and Black a scoring % of 43.7%. So clearly 11...Na6 provided a much better scoring % advantage to Black compared to 11...Nc6

After 11...Nc6 only 2 games continued with 12.Qe2 Qc7 13.Kb1Na7 when they reached the following position:

click for larger view

Z Andriasian vs Zhou Jianchao, 2006 continued with 14.Bxa7 and ended in a draw and this game continued with 14.Ba4 b5 15.Bxb5 Nxb5 16.Nxb5 Qb8 17.c4 to reach the following position:

click for larger view

But Opening Explorer "only" has about 950K games and the more comprehensive ChessTempo database (https://old.chesstempo.com/game-dat...) has almost 4M games and about 1.8M master-level games (both players rated 2200+). It has 60 games with 11...Nc6 but after 12.Qe2 Qc7 13.Kb1Na7 it has only 1 game, the aforementioned Z Andriasian vs Zhou Jianchao, 2006.

I don't think even today I would consider any chess engine, at least no classic chess engine, to be capable of strategizing if by "strategy" you mean developing a plan of action or policy designed to achieve a major or overall aim; in this case post a knight on d5. Classic chess engines just calculate (and calculate, and calculate, and ...) and select as the move to play the first move in all the lines it considered that resulted in the highest evaluation in the minimax sense. Perhaps neural-network based engines or engines using Monte Carlo Tree Search (MCTS) methods could be considered as being capable of coming up with a long term stragegy.

Besides, I'm not sure that in this case <attempting> to place a knight on d5 as a long-term strategy gives White any advantage. Black certainly knows what White is trying to do in a position where Black has a backward d-pawn on a half-open d-file and will focus on trying to prevent the occupation of d5 by a piece. In pretty much all the master level games I've seen recently when White tries to occupy d5 with a piece he fails; after a sequence of exchanges it's a White pawn that ends up occupying d5. And this usually entails Black giving up his LSB and not only does Black give White the advantage of the 2 bishops but finds himself with a bad DSB given the black pawns on d6 and e5.

But in compensation Black no longer has a backward pawn on the half-open d-file and the resulting semi-closed position typically favors the Black knight rather than the White LSB. And while White has greater space and q-side play Black has the greater potential on the k-side if he can force ...f5, something made easier by the disappearance of White's Pe4. The resulting positions have more of a King's Indian character than a Sicilian character, and are probably not the type of positions White had in mind when he opened 1.e4. I've seen that most of these games end in a draw.