Thursday, July 31, 2014

When in doubt, Bxh7 (Part 3)

If anyone still recalls one of the articles I wrote an incredibly long time ago regarding the attack against a castled king (http://nushsblackknights.blogspot.sg/2013/08/how-to-attack-part-2.html), we had discussed about the advantages and drawbacks of using the h7/h2 focal point for an attack. This square is very easily accessible to the attacker, but the difficulty lies in preventing the escape of the enemy king after the clearing of the square. This is especially true in the case of the Greek Gift sacrifice, since after Bxh7 (or Bxh2 for White) followed by Kxh7 the defender often has many squares for his king to run to (Kg8, Kh8, Kg6 and Kh6) and the attacker must know how to respond to all of them!

As such, it is important for us to know how to calculate the many variations that follow after the launch of the sacrifice, and hopefully we will be able to uncover the many details that explain why this tactical motif continues to mystify us even till this day.

Today, we will look at the variations where the defending king retreats back into his shelter (...Kg8/Kg1 or Kh8/Kh1). When this happens the resulting attack is often easy to execute since the attacker's Queen and Knight work together to make a formidable strike force. A look at the very first example from Part 1 can confirm this quickly:

Position after 7... O-O

And if you can recall, the variations after 8. Bxh7 Kxh7 9. Ng5+ Kg8/Kh8 ended quickly:

8... Kh8 9. Qh5+ Kg8 10. Qh7#

8... Kg8 9. Qh5 Qxg5 (in order to prevent mate on h7) and Black loses the Queen.

However, such a position can only occur in an attacker's dream, and in reality the differences in a position often make the subsequent variations after Kg8/Kh8 (Kg1/Kh1 if Black is the attacker) much more complex than they seem. In the following position from an Advance French variation, White seems to be facing problems since Black has a potential escape square on f8. But fortunately for White, other aspects of his position, such as the possibility of the rook lift to e3, help him create a successful mating attack:

White to move


1. Bxh7+! Kxh7

After 1... Kh8 White simply plays 2. Ng5 with 3. Qh5 to follow

2. Ng5+ Kg8

Or 2... Kg6 3. Qd3+ f5 (3... Kh6 4. Qh7#) 4. exf6+ Kxf6 5. Qf3+ after which Black will collapse very soon

3. Qh5 Nf8

Black cannot defend the f8 square; for example 3... Qe7 leads to 4. Qh7+ Kf8 5. Qh8#

4. Qxf7+ Kh8
5. Re3!
1-0

The rook lift decides matters; there is no stopping 6. Rh3+ followed by mate.

In the next example, Black (the attacker) also faces problems since White's bishop on c1 seems to be able to help defend the h2 square, thus making Qh4 seem impractical. But fortunately for Black, he has the additional option of Qe4+ and other active factors which allow his attack to succeed:

Black to move


1... Bxh2+
2. Kxh2 Ng4+
3. Kg1

3. Kh3 falls quickly to Nxf2+ winning the queen, while after 3. Kg3 Qe5+ 4. f4 Qh5 5. f5 Qh2+ 6. Kxg4 h5+ 7. Kg5 Qg3+ 8. Kxh5 g6+ 9. fxg6 Re5+ it is not hard to spot a checkmate for Black here.

But now what? Black cannot play 3... Qh4 since 4. Bf4! foils his plans immediately by bringing an extra defender to the h2 square. Fortunately, Black has a way to deny the enemy bishop access to the h2-b8 diagonal:

3... Qe5!
4. f4 Qh5
5. Rf2 Qh1+!
6. Kxh1 Nxf2+
0-1

It is interesting to note that in our previous two examples, the attacker's plans would not have succeeded if the pawn were on h5 (for the first position) or h4 (for the second position). For the former, this would have denied White the opportunity to utilize his rook lift effectively, while in the latter the same goes for Black's 4... Qh5.

And thus here are some of the interesting factors about the position which one has to consider before he can launch a successful sacrifice. In our next article, we will extend our discussion to the more complicated examples: When the defending king has the option of using the g6/g3 or h6/h3 squares as escape routes.

Links:
Part 1: http://nushsblackknights.blogspot.com/2014/07/when-in-doubt-bxh7-part-1.html
Part 2: http://nushsblackknights.blogspot.com/2014/07/when-in-doubt-bxh7-part-2.html

Sources:
"Art of Attack in Chess" by Vladimir Vukovic

Tuesday, July 29, 2014

4 basic but important tips on opening theory

Let us put whatever we have discussed in today's lesson up here to share with the rest of the team. Once again, I emphasize on the word BASIC, so you should have no problem understanding as you look through them.

While the number of possible openings in chess is simply so wide and numerous that it is almost impossible to memorize every single line (and I do NOT recommend brute-force memorization of opening lines without first getting to understand the plans behind them!), the basic idea behind any opening is the same: To mobilize one's forces and attain a lead in development so that one has an advantage in the middlegame. As such, here are 4 simple but important tips which we should all be familiar with if we wish to do well in the early stages of the game:


1. Pay close attention to your development and tempo

The most fundamental idea in the opening; at the start of the game both armies mobilize their forces for the upcoming assault. If one is able to gain a lead in development and tempo it allows him/her to seize the initiative and possibly launch an attack first before his opponent is able to fully consolidate himself.

Point 1 can be further divided into 4 further subpoints:

(a) Develop all your pieces

I don't think this really needs elaboration.

(b) Try not to move each piece multiple times in the opening

The idea in the opening is to mobilize ALL your pieces; moving pieces multiple times without any good reason only serves to slow down your development. As quoted by Aaron Nimzowitsch in "My System": "How undemocratic for instance, it would be to let one of your officers go for a long walking tour, while the others kicked their heels together at home and bored themselves horribly. No, let each officer make one move only, and... dig himself in."

(c) Don't push pawns unless it aids you in your development/ slows down the opponent's development.

Similar to the idea in (c); pushing pawns unnecessarily only wastes precious time which you could have used to develop your pieces. The only times which you should push pawns are when it helps clear the way for your pieces to develop (e.g. pushing the centre pawns in the opening) or as a prophylaxis against possible enemy incursions (e.g. a timely h3/h6 to prevent the annoying bishop pin on g4/g5)

(d) Try to develop pieces and make threats at the same time if possible

If you can slow down your opponent's development so that you can gain a lead, why not? I have included a good example of this in the sample game at the end of this article.


2. Do not exchange unnecessarily

This is a very common mistake among beginners; I have seen too many games where young kids mindlessly exchange pieces, not realizing it only helps their opponent improve his/her position. This is especially true for the opening where pieces are just being developed and their relative strengths are just being ascertained.

One simple example will the position after 1. e4 e5 2. Nf3 Nc6 3. d4 exd4 4. Nxd4 Nf6 5. Bg5 d6:

Position after 5... d6

White's bishop pins the knight, and now 6. Bxf6?! is questionable since after 6... Qxf6 Black retakes and develops his Queen at the same time. A fine case of exchanging without thinking!

This rule is a very simple one that we all should have committed to memory, yet it gets flouted every day by so many amateur players.


3. Try to control, if not occupy, the centre

In the early stages of the game it is good practice to stake a claim to the centre of the board (consisting of the 4th and 5th squares of the c to f files), since it gives you ample space to mobilize your pieces and possibly launch an attack later on. On the other hand, ceding control of the centre gives you a cramped position that may be a pain to defend in the middlegame.

The two types of approaches which one may have towards the concept of centre control are the Classical and Hypermodern theories. In Classical theory, the idea is to control the centre by occupying it with pawns, before using pieces to support the pawn centre (hence the prevalence of opening moves like 1. e4 e5 and 1. d4 d5). This is also the most common idea that is taught to young beginners when they start learning chess.

On the other hand, Hypermodern theory states that control need not always be established through pawns in the centre; pieces can also use their long range abilities to control central squares from a distance. An even more counterintuitive method will be to allow the enemy to set up his pawn centre, before counterattacking it with your own pawns and pieces.

Because of the complexity of the Hypermodern theory, my advice to weaker players is to play safe and go with the Classical theory for now, and learn how to set up a strong pawn centre. Of course, if you do want a better understanding of Hypermodern theory and how to play such openings, then I will recommend you to the following link: http://nushsblackknights.blogspot.sg/2013/07/hypermordernism-and-kings-indian-part-1.html


4. Castle early, unless it is wrong to do so

Once again this doesn't need much elaboration; castling helps to keep the king safe and develop the rooks. While in rare instances it is indeed acceptable not to castle (see http://nushsblackknights.blogspot.sg/2013/10/the-right-time-to-castle.html for some examples of when it is actually better not to castle/delay castling), the best piece of advice will be to castle early in most positions.

...

To end off we will look at a sample miniature taken from Aaron Nimzowitsch's "My System". It emphasizes the importance of early development, and warns of the dangers that grabbing pawns too early in the opening (and thus lagging behind in tempo) may cause.

Nimzowitsch has helpfully provided ample annotations in his book, and I will include most of them over here.

Aaron Nimzowitsch vs Semion Alapin
Casual Game 1914


1. e4 e6
2. d4 d5

The French Defense: A simple example of exerting control over the centre (Point 3)

3. Nc3 Nf6
4. exd5 Nxd5

Nimzowitsch: "Surrender of the center"

5. Nf3 c5

Nimzowitsch: "To 'kill' the Pawn. 'Restraint' might have been effected by, say ...Be7, ...O-O, ...b6, ...Bb7."

Personally I don't like this move; while it looks aggressive, it also violates one of the fundamental points we went through just now: Don't push pawns unnecessarily unless it aids in development.

6. Nxd5 Qxd5
7. Be3 (D)


Position after 7. Be3

Developing and making threats at the same time helps to slow the opponent down. Here the threat is dxc5 winning a pawn.

7... cxd4

Nimzowitsch: "Disappearance of tempo spells loss of time."

8. Nxd4 a6
9. Be2 Qxg2

Nimzowitsch: "Stealing a Pawn. The consequences are grievous."

10. Bf3 Qg6 (D)


Position after 10. Qg6

White is a pawn down, but he has developed most of his pieces. Black, in contrast, has only a mobilized Queen which is dancing around in the middle of nowhere (and violates the rule not to move a piece more than once in the opening!)

11. Qd2 e5

Nimzowitsch: "The crisis. Black means to be rid of the unpleasant Knight, so that he may in some measure catch up in development."

12. O-O-O! exd4
13. Bxd4

White has castled his king to safety and mobilized all his forces, while Black's pieces are still sleeping on the first rank and his king is stuck in the centre. Quite a good compensation for a pawn and a knight!

13... Nc6
14. Bf6!

Nimzowitsch: "Travels by express. Any other Bishop move could have been answered by a development move, whereas now there is no time for this; Black must take."

14... Qxf6

14... gxf6 15. Bxc6+ bxc6 16. Qd8#

15. Rhe1+ (D)

Position after 15. Rhe1+

Nimzowitsch: "Play in the King and Queen files at the same time. The danger of a breakthrough is great."

15... Be7

Or 15... Be6 16. Qd7#

16. Bxc6+ Kf8 (D)

White to move and mate in 2

Or 16... bxc6 17. Qd8#

Now, try to solve the mate in 2 puzzle before scrolling down for the answer!

.
.
.
.
.
.
.
.
.
17. Qd8+Bxd8
18. Re8#
1-0

An elegant illustration of the fate of one who does not develop his pieces properly

...

So that was 4 basic but extremely useful tips for one to keep in mind, regardless of whatever opening line you choose. All the best!

Sources:
"My System: 21st Century Edition" by Aaron Nimzowitsch

Friday, July 25, 2014

Term 3 Tactical Presents (Part 1)

Are y'all so bored of school work that you're looking for something that's more worth spending time on? Then here are 8 more presents of mixed difficulty for you to try out. Take this time to hone your tactical vision, especially since we'll be heading down to Rulang again in 2 months time.

Puzzle 1: White to move and mate in 4

Puzzle 2: Black to move and mate in 4

Puzzle 3: White to move

Puzzle 4: Black to move

Puzzle 5: White to move and mate in 3

Puzzle 6: Black to move

Puzzle 7: Black to move and mate in 3

Finally, here's an interesting endgame study for y'all to try out: White to move and mate in 3!

Puzzle 8: White to move and mate in 3


Saturday, July 19, 2014

The 7th Rank: Black Knights Internal Tournament Round 16

Most of my assignments for the weekend have (miraculously) been completed, and since I happen to have a bunch of scoresheets lying in my file I decided to spend some time looking through the games and seeing whether there was anything worth analyzing (no, dropping queens and rooks don't count as games worth analyzing). And fortunately one game hasn't failed my expectations, so I have decided to post it up here for y'all to take a look. Most of the analysis down here has been done with the help of our good friend, Deep Fritz 12.

To protect the identity of the players involved, I have replaced their real names with pseudonyms.

Mohawk vs Salamander
Black Knights Internal Tournament 2014, Round 16


1. d4 d5
2. Bf4 Bf5
3. e3 Nc6
4. Bd3 Bxd3
5. Qxd3 e6
6. Nf3 Nf6
7. O-O Bd6
8. Bxd6 Qxd6
9. a3 O-O
10. Nbd2 Rfe8 (D)

Position after 10... Rfd8

The game resembles a quiet form of the Queen's Gambit Declined; in most positions like this Black usually places his knight on d7 rather than c6, so as to clear the way for a future c5 pawn thrust.

11. c4 dxc4
12. Nxc4

The semi-open c file will become an important battleground for both sides.

13... Qd5
13. Rfd1

13. Nce5 is possible, but after 13... Nxe5 14. Nxe5 c5 (exploiting the hanging position of White's Queen) 15. Rfd1 Rac8 Black prepares to take control of the c-file that will open up after the exchange.

13... Rad8
14. Qc2 Qe4

A very interesting alternative here will be 14... Ne4 15. Nfe5 where the position becomes rather messy, with both sides preparing to undermine the enemy outposts with f3 and f6 respectively. Now if Black decides to do this immediately with 15... f6!? then the reply suggested by Fritz is 16. Rac1 (D)

Position after 16. Rac1

It looks like a passive move, but in fact 16. Rac1 is a very sneaky attempt by White to exploit both the semi-open c-file and the soon-to-be-opened d-file. White's Queen and Rook assist the e5 knight in making an indirect attack on Black's Knight, which is in turn guarded by only 2 defenders and pinned to a hanging pawn behind him. Furthermore, White's d-file rook is also looking threateningly at the Queen on d5, which is already overloaded trying to babysit both her knights!

So for example after 16... Nd6 (16... fxe5? 17. dxe5 and the threat along the d-file materializes; Black must give up either his Queen or Knight) 17. Nxd6 Rxd6 18. Nxc6 Rxc6 19. Qa4 (another X-ray, looking at the unprotected rook on e8!) Ra8 20. Rxc6 Qxc6 21. Qxc6 bxc6 the resultant endgame is better for White since he has the better pawn structure.

So instead of 15... f6 a better continuation for Black might have been 15... Nd6 16. Nxd6 Rxd6 before preparing for a f6 thrust later on.

15. Rac1

15. Qxe4?! Nxe4 allows White to centralize his knight with gain of tempo.

15... Qxc2
16. Rxc2 e5
17. Rcd2

Don't look my brothers, there's gonna be lots of bloodshed!

17... exd4
18. Nxd4 Nxd4
19. Rxd4 Rxd4
20. Rxd4 h6
21. h3 b6
22. Rd3 Ne4?

Looks active, but this also relinquishes control of the d7 square and allows White's rook to invade the 7th rank! The alternative suggested by Fritz was 22... b5 23. Na5 c5 24. Nc6 a6 and although White seems more aggressive, the endgame still looks rather drawish.

23. Rd7! (D)

Position after 23. Rd7

Remember how quite some time ago we saw an example of the power of a rook on the 7th rank (http://nushsblackknights.blogspot.sg/2013/12/revising-basic-rook-endgames-part-3.html)? Here we go again: The rook on the 7th rank fences off the enemy king, attacks the enemy's vulnerable pawns, and forces the opposing rook to relegate to a passive role of defending the pawns. And by now, we should all know the superiority of active rooks over passive ones.

23... Rc8
24. Ne5 f6
25. Nc6!

The tactical blow that decides the game in White's favour: The dual threat of Nxa8 and Ne7+ has no good reply.

25... Nc5
26. Ne7+ (D)
1-0

Position after 26. Ne7+

After 26... Kf7 27. Nxc8+ Nxd7 28. Nxa7 White wins a pawn and gets the better endgame.

I love this apparently simple, yet so instructive game that clearly illustrates the theme of the rook on the 7th rank.

Sources:
http://www.amazon.com/Sylvester-Stallone-Barechested-Machine-Transparency/dp/B00GSBTU0Q

Saturday, July 12, 2014

When in doubt, Bxh7 (Part 2)

In the first part we have looked at the basic example of the Greek Gift Sacrifice presented in its simplest form. Today, we will take a deeper look into what are the conditions needed for this sacrifice to work, and when is it correct (or incorrect) to unleash it.

Basic Conditions needed for the sacrifice to work

In his classic work "Art of Attack in Chess", Vukovic has taken great pains to explain the conditions needed for the classic bishop sacrifice to work, and thus I must give him due credit for what is to be presented in this article.

To make thing easier to visualize I will use the same position that we saw earlier:

Pieces involved in the assault

For the gambit to be successful the attacker should have (apart from his bishop) a Queen and a Knight involved in the follow-up assault. A quick glance at the above diagram should be clear enough: From its natural developing square, White's knight can quickly hop to g5 to hit the h7 square, where it is protected by the bishop on c1. At the same time, it also clears the diagonal for White's Queen to access h5. This combination of Queen + Knight assault is the most common, and most direct method of hunting down the enemy king once the h7/h2 square has been cleared.

From the attacker's point of view, it is not just about having sufficient pieces to stage the follow-up assault; the opponent's position must also have certain characteristics in order to ensure a successful execution:

Vital squares in the enemy position

I have highlighted several key squares that play an important role in the attack. The yellow ones should be quite intuitive; those pawns on g7 and h7 should have nothing blocking their way, though in rare occasions a bishop may be in place of the pawn on g7, or that there may be no pawn on h7 at all. But far more important is the f6 square (f3 in the case of a attack against White), which is a natural developing point for Black's knight where it helps to defend the h7 square. Notice how the knight needs to be chased away from this critical square (for obvious reasons) before the sacrifice on h7 can be successful.

Another key factor for the success of the sacrifice is the fact that it would be detrimental for the opponent to decline the gambit. If the defender has the liberty of simply replying Kh8/Kh1 with no major side effects (or worse still, being able to turn the tables on the attacker) then it does not make much sense for the attacker to invest this endeavour. In the earlier example, we have already seen that should Black reply to 7. Bxh7 with 7... Kh8, then his position falls apart after 7... Kh8 8. Ng5 g6 9. Qg4 Qe7 10. Qh3 Kg7 11. Bxg6, thus justifying the effectiveness of the gambit in this position.

On the other hand, below is a counter-example of what can possibly go wrong if the attacker does not take into account the possibility of his opponent declining the sacrifice:

White to move

White's bishop is in trouble, and the natural move that comes to mind would be 1. Be2. But instead, White sees a chance to attack and makes an ill-calculated sacrifice:


1. Bxh7+?

White was hoping for 1... Kxh7? reaching the typical mating positions after 2. Ng5+ Kg6 3. Qg4 +-. But what he failed to take into account was that Black could simply reply with:

1... Kh8!
2. Ng5

The bishop has nowhere to go to, and after 2. Qe2 Bxf3 3. Qxf3 Kxh7 Black is up in the exchange. Notice that Black only takes the bishop after eliminating his opponent's knight, thus crippling White's ability to press on the attack.

2... Qxd1

The same motif as explained before: Exchange off possible attacking pieces before taking the bishop

3. Rfxd1 g6
0-1

And there is no good reply to 4... Kg7 followed by 5... Rh8, trading two minor pieces for a rook with Black gaining the upper hand.

...

One last thing I would like to highlight is that the Greek Gift sacrifice does not always need to be a precursor to a mating attack; sometimes, it can be used simply as a way to gain a simple advantage (such as winning material). This idea manifests itself in the following position:

Black to move

Here Black can "sacrifice" his bishop with 1... Bxh2+, and if White accepts with 2. Kxh7 then Black wins the Queen after 2... Qd6+! (2... Ng4+ is also possible but after 3. Kh3 Black can't really follow up the attack). Thus White must decline with 2. Kh1, and after the series of exchanges Black will be a pawn up with an advantage in the endgame.

In this series I want concentrate mainly on the concept of the mating attack rather than that of winning material; as such, in our next article we will take a look at the subsequent variations that have to be taken after the sacrifice has been made.

Links:
Part 1: http://nushsblackknights.blogspot.com/2014/07/when-in-doubt-bxh7-part-1.html

Sources:
"How to Calculate Chess Tactics" by Valeri Beim
"Art of Attack in Chess" by Vladimir Vukovic

Friday, July 4, 2014

When in doubt, Bxh7 (Part 1)

For a moment I wanted to add #yoloswag but I guess the title speaks for itself. The legendary bishop sacrifice on h7 (or h2 for Black) has become one of the classical motifs that symbolizes the art of attack in chess. In practice, the sacrifice of the bishop helps to open a file in the enemy's castled position, thus allowing the attacker's pieces (usually the Queen and the Knight) to deliver the mating attack.

As such, I want to dedicate the next couple of articles to this classical sacrificial attack, which is so well-known that it has been given a name of its own: The Greek Gift Sacrifice (named after the legend of the Trojan Horse).

Commander, I think I need the toilet...

For the uninitiated, here is the sacrifice presented in its pure, unadulterated form after  1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. e5 Nfd7 5. Nf3 Bb4 6. Bd3 O-O?

Position after 6... O-O

7. Bxh7+! Kxh7

White could decline the sacrifice with 7... Kh8, but due to poor king safety his position falls apart after 8. Ng5 g6 9. Qg4 Qe7 10. Qh3 Kg7 11. Bxg6!

8. Ng5+

And now Black is forced to choose between mate and the loss of enormous amounts of material:

8... Kh8 is suicide after 9. Qh5+ Kg8 10. Qh7#

8... Kg8 9. Qh5 forces Black to give up the queen with 9... Qxg5 in order to prevent mate on h7

8... Kh6 loses the Queen after 9. Nxf7+

8... Kg6 is the most resilient reply, but after 9. h4 Black has to face the threat of 10. h5 Kh6 (10... Kf5? 11. Qf3#) 11. Nxf7+ forking the king and queen. With Black's king in the open it should not be too difficult for White to find a lasting attack.



Looks elegant? That was simply a kickstart to whet our appetite. In subsequent articles, we will take a deeper look into what conditions are required for this sacrificial attack to work, and examine cases where this classical motif had been successfully (or unsuccessfully) executed.

Sources:
http://www.keiththompsonart.com/pages/trojanhorse.html
"How to Calculate Chess Tactics" by Valeri Beim
"Art of Attack in Chess" by Vladimir Vukovic