Calculating Forcing Moves: Defensive Idea 3, Part 2 (Prepare to Move)

When your opponent creates a (real) threat, or you are considering creating one against your opponent, there are five defensive ideas to consider.  We have already looked at different ways to implement the first two defensive ideas:  Idea 1 (capture the attacking piece, pin the attacking piece, deflect the attacking piece), or Idea 2 (block the attacking piece).  We also explored the third basic idea of moving out of the attack.

In this post we will look at a position where we "prepare to move".  These moves are possible when the threat is one move away, and you have time to move another piece out of the way so that you can escape to, or through, that square when the threat is played.

The general process is to evaluate the position, identify and prioritize all threats, and then to use the five defensive ideas to identify specific candidate moves.  Next, calculate each candidate move to the end and evaluate the final positions (material and activity).  As you progress through the candidates, keep in mind the "king of the hill" (KOTH) candidate move to help you pick the best at the end.

The below position is from Ward Farnsworth's wonderful chesstactics.org website, but the analysis here is my own!  We'll follow the same approach as usual:  evaluate the position, identify and prioritize all threats, use the five defensive ideas to identify specific candidate moves, and calculate each candidate to find the best (or least bad) reply.

Black just played ...Qe7.  White to move.

5k2/pb2qp1p/1p6/6R1/3p4/8/PP4PP/R2N3K w - - 0 1

Let's evaluate the position and then find all of black's threats.  Black is up a queen and a pawn vs two rooks, and black's pieces and passed pawn are significanly more active than white's pieces.  Black is playing for a win and white is fighting to draw.  Black has two concrete threats:  checkmate (...Qe1#) and win a rook (...Qxg5).  Of those two threats, the checkmate is the priority.  Let's look at the five defensive ideas to see what candidate moves we find, and then pick the best move.  Hopefully we can avoid checkmate AND save the rook.

Idea 1 (capture, pin, deflect):  none.
Idea 2 (block):  1. Re5 and 1. Ne3 directly block the queen from getting to e1, while 1. Rf5 "prepares to" block on the next move with Rf1.
Idea 3 (move):  since the mate is one move away we can look at direct king moves, as well as moves that create an escape square ("prepare to move").  The king only has one move, but 1. Kg1 does not allow the king to escape checkmate because f2 will be covered by the queen on e1.  White can also "prepare to move" his king by creating an escape square on h2 (the bishop is taking away g2), by playing 1. h3 or 1. h4.
Idea 4 (defend):  white can defend the mating square on e1 with his rook on a1, if the knight can get out the way.  We already have 1. Ne3 from above, which we now see might accomplish two things at once (block the queen, and allow the rook to defend e1).  The knight has two other possible squares to move to 1. Nc3 and 1. Nf2.
Idea 5 (counterattack with an equal or greater threat to WIN, DRAW, DEFEND):  there is not time to create equal threat.  A greater threat would have to start with a check, and white has 1. Rg8+.

The five defensive ideas have given us eight actual candidate moves to calculate further:  1. Re5, 1. Ne3, 1. Rf5, 1. h3, 1. h4, 1. Nc3, 1. Nf2, and 1. Rg8+.  Let's start with white's most forcing candidate move 1. Rg8+:

1...Kxg8 (only).  White has lost a rook and has no more checks.  He therefore cannot force a draw by perpetual and is not able to reposition his other pieces to defend using the other four ideas.  Reject 1. Rg8+.

None of the remaining seven moves seem particularly more forcing than the others, so let's just go through them in the order that we discovered them.  1. Re5:

1...Qxe5 appears to be black's most forcing reply.  Black is again threatening mate with no new defensive options available and after 1. Nf2 black is ahead a queen and a (passed) pawn vs a rook, so 1...Qxe5 appears to refute white's candidate.  Reject 1. Re5.

The other block we found also defended e1, so let's next look at the interesting 1. Ne3:

1...Qxg5 appears to be black's most forcing reply, so let's see if that is a refutation.  White is now down more material and black again has two concrete threats:  to capture the knight and, should the knight move, to deliver checkmate with Qxg2#.  Simply pushing the d pawn also looks like a fun attacking idea for black, and would give white a third threat to have to defend against.  Saving the knight (and defender of g2) is white's first priority so let's look at the five defensive ideas and see if any work.  White cannot capture, pin (2. Rd1 doesn't work), deflect, or block the pawn or queen.  He can only move the knight to two squares that do not immediately allow mate (2. Ng4, and 2. Nd5).  He can defend the knight with 2. Re1 but, after 2...dxe3 the rook cannot recapture on e3 because of the mate threat on g2.  That only gives us two defensive ideas, both of which just delay the mate in 1 by one more move.  Then after the obligatory 3. Rg1, black's two threats (passed pawn and checkmate) will make for a simple win, and we can safely say that 1...Qxg5 refutes white's candidate.  Reject 1. Ne3.

The last blocking idea we found prepares to block on f1 after Qe1+, but seems easily refuted.  After 1. Rf5:

1...Qe1+ 2. Rf1 (only) Qxf1#.  Yup, easily refuted.  Reject 1. Rf5.

Next up would be the two candidate moves that create an escape square for the white king, and prepare for him to move out of the check.  Let's look first at 1. h3:

1...Qe1+ is black's most forcing move, but after the king moves away with 2. Kh2, black has no clear follow-up.

1...Qxg5 appears stronger for black, since he is now up even more material and is threatening checkmate on the next move with ..Qxg2.  After considering all five defensive ideas, we find whites' only move to prevent the mate is 2. Ne3 following by 3. Rg1.  So while 1...Qe1+ does very little for black, 1...Qxg5 is a crushing refutation.  Reject 1. h3.

The other block seems much more interesting because it also defends the rook on g5, so let's see if black has anything left after 1. h4:

1...Qe1 (again black's most forcing move) 2. Kh2 (only) Qxh4+ 3. Kg1 (only) Qxg5 4. Ne3 (forced) dxe3 5. Kf1 (only way to prolong...) Qxg2+ 6. Ke1 Qf2+ 7. Kd1 (only) Qd2#.  Reject 1. h4.

The final two candidate moves (1. Nc3 and 1. Nf2) come from the idea of defending the e1 mate square.  Since 1. Nc3 puts the knight en prise, let's see what we get with 1. Nf2:

1...Qxg5 (most forcing) 2. Rg1 (forced) and now Qd2 appears simple and wins at least the b pawn (defending the pawn with 3. Nd1 allows Bxg2+ 3. Rxg2 (only) Qxd1+ 4. Rg1 (only) and now black has won a pawn and traded the minor pieces but also has ...Qf3+ followed by ...d3.).

White's last defensive hope is 1. Nc3:

1...Qxg5 (most forcing) 2. Rg1 (forced) and now black just picks off the c3 knight, making this line worse than 1. Nf2.

After looking at eight candidate moves, we can confidently resign knowing that we have not missed a single defensive opportunity for white.  If we felt compelled to play on for some sadistic reason, the two least bad moves would be either 1. Rg8+ or 1. Re5, which "only" leave black ahead a queen and passed pawn vs a rook.  All other moves are worse than that!  In future posts I will discuss ways to track multiple evaluations in your head while calculating, including positions where all of your choices are relatively bad or your best move is only slightly better than the second best!

Calculating Forcing Moves: Defensive Idea 2, Part 2 (Prepare to Block)

When your opponent creates a (real) threat, or you are considering creating one against your opponent, there are five defensive ideas to consider.  We have already looked at three different ways to implement the first defensive idea of going after the attacking piece:  capture the attacking piece, pin the attacking piece, or deflect the attacking piece.  In an earlier post we looked at the second defensive idea of blocking the attack.

In this post we will look at a position where the threat is not immediately on the board but is likely to be played on the next move (like a mate-in-1 threat), and we will use the idea of "prepare" to block" by rearranging our pieces to allow a block if the threat is executed.  

The general process is to evaluate the position, identify all threats, and then to use the five defensive ideas to identify specific candidate moves.  Next, calculate each candidate move to the end and evaluate the final positions (material and activity).  As you progress through the candidates, keep in mind the "king of the hill" (KOTH) candidate move to help you pick the best at the end.

The next position uses the same basic defensive idea of blocking an attack, but also demonstrates how blocking with a like piece can gain time and be more forcing than blocking with other pieces.

Black just played Qe6+.  White to move.

r4r2/4ppBk/p2pq1p1/1p5n/4P2P/P4P2/KPPQ4/3R1BR1 w - - 0 1

Let's evaluate the position and then find all of the threats.  Pawns are equal, both sides have one queen and two rooks, and although white is currently up a minor piece his bishop on g7 is en prise and he is in check.  Will white have time to save his bishop?  Black's threats are the check, and then to capture the g7 bishop on his next move, after which material will be equal.  White is also threatening checkmate with Qh6#, but needs to address both the check and the threat to his g7 bishop.  Let's look at white's three defensive ideas (you can't defend or counterattack when in check!) to see what candidate moves we find, and then pick the best move.

Idea 1 (capture, pin, deflect):  none.
Idea 2 (block):  searching square by square between the queen and the king we find four moves that block the check: 1. Qd5, 1. c4, 1. Bc4, and 1. b3.
Idea 3 (move):  1. Ka1, and 1. Kb1
Idea 4 (defend):  n/a
Idea 5 (counterattack with an equal or greater threat to WIN, DRAW, DEFEND):  n/a

Let's look at the easiest to calculate moves first (instead of the most forcing).  After both king moves, black just captures the bishop (if 1. Ka1/Kb1 Kxg7) and the position is materially equal.  This is our KOTH.

Now let's look at calculate each block and see if we get anything better than our KOTH evalulation of equal.

If 1. Qd5 white has no threats (because Qh6# is no longer an option) and black can simply take the bishop, or can take the queen first with check and then the bishop.  Black has nothing better, and this line is no better (and no worse) than our KOTH.

If 1. c4 white now has one threat to deliver mate with Qh6#.  Black can easily address the one threat threat by capturing one of the attackers with Kxg7.  Black has nothing better, and this line is no better (and no worse) than our KOTH.

If 1. b3 again white now has one threat to deliver mate with Qh6#.  Black can easily address the one threat threat by capturing one of the attackers with Kxg7.  Black has nothing better, and this line is no better(and no worse) than our KOTH.

If 1. Bc4 white now has two threats - to capture the queen, and to deliver checkmate.  The checkmate is the greater threat so lets look at black's defensive options.

Idea 1:  Black can capture the g7 bishop with 1...Kxg7 or 1...Nxg7.
Idea 2:  Black can block the white queen from getting to h6 with 1...Nf4 and 1...g5.
Idea 3:  Black can defend the mating square on h6 again with 1...g5.
Idea 4:  The black can escape with 1...Kg8.
Idea 5:  Black's counterattack ideas must begin with a check, given white's checkmate threat, and black only has one:  1...Qxc4+

Of black's six candidate moves we can quickly dismiss five -- the two captures, the two blocks, and the move -- because they all immediately lose the queen.  That only leaves black's one counterattack idea, so after 1. Bc4 Qxc4+:

We have the same exact same situation as in the starting position, except now white is down an entire piece and, as soon as white addresses the check, black is going to capture the g7 bishop.  This would leave white down an entire piece and appears to refute white's 1. Bc4, no?

Here again white has two king moves (both of which leave white down a piece, and is worse than our KOTH), and one block with his tiny pawn.  However, that pawn block comes with a punch, because it is again attacking black's queen!  So after 1. Bc4 Qxc4+ 2. b3:

After this simple block by the simplest of pieces, the roles have again been reversed and now black has to deal with two threats!  The checkmate threat takes priority, and no matter what black tries the best he can do is go desperado and snatch a pawn and the g7 bishop for his queen.

This position demonstrates very clearly the power of blocking with a like-piece, and how you can turn a simple pawn block into a game-winning counterattack!  This position also shows the risks in counterattacking!  Looking at the original position, black should have calculated his move Qe6+ a bit longer.  It clearly would have been much safer for black to have just captured the g7 bishop instead of going for a some fancy counterattack/intermezzo!!

Finally, the last position demonstrates additional blocking options when the threat is one move away.  In this position you can expand the block concept to moves that "prepare to block", by either moving a piece into position to block once/if the threat is played, or by moving the king out of the way to allow a piece to block.

I'll leave this last one as a puzzle.  It is white to move:

5rk1/2p4p/Bpn1p3/p2PP1q1/3PP3/PP3p2/1BQ2P1r/2RR1K2 w - - 0 1

[HIGHLIGHT TO SEE ANSWER:  White's only defense is to move his king to allow the a6 bishop to block: 1. Ke1 Rh1+ 2. Bf1]

Calculating Forcing Moves: Defensive Idea 5 - Counterattack to DRAW (repetition)

In this series of posts we are looking at “counterattacking to DRAW”, which is using Equal or Greater Threats to force three types of drawn positions:

• Draw by stalemate;
• Material draw (equal material, fortresses, etc); and,
• Draw by repetition.

In the last two posts we looked at positions where there were clear threats on the board, and we created an EGT that allowed us to force drawn positions by stalemate and by reaching a drawn endgame.   In this post we’ll look at a position where the best move is to use a series of EGTs to force the opponent to repeat the position, resulting in a draw.

Black just played 1…Kxf4.  White to move.

2n5/3pB3/p3p3/2Q2n2/3p1kb1/1r6/q4PBK/3r4 w - - 0 1

Let's evaluate the position, and then find and prioritize all of black's threats.

Evaluation:  White is clearly losing. Black is up two rooks, a knight, and three pawns.   White is considering whether he should do the noble thing and resign.  The only thing going for white is his extreme lack of pieces and almost complete immobility…this immediately brings to mind stalemate themes.

Threats:  Black’s threats are many, but the fastest forced checkmate I can find is 2…Rh3+ 3. Bxh3 (only) Qxf2+ 4. Bg2 (only) Qg1#.

Let's look at the five defensive ideas to see what options white has to reply to the threat.

Idea 1 – do something to the attacking pieces (the g4 bishop, both rooks, and the queen).  We cannot capture, pin (absolute, given the mate threat), or deflect any of black’s attacking pieces.

Idea 2 – block the attacking pieces (the g4 bishop, both rooks, or the queen, from getting to h3, f2, or g1).  White has five blocks (2. Qc3, 2. Qc2, 2. Bf3, 2. Bg1, and 2. f3), but in all cases black simply captures with the queen or rook, which reinstates the same threat.  If the bishop leaves g2 (for 2. Bf3 and 2. Bg1), this simply allows a capture-check and a new forced mate (2…Qxf2+ 3. Bg2 Qg1#)

Idea 3 – move the piece being attacked (the white king).  The king has zero legal moves. Creating an escape square for the king by moving the bishop somewhere threatening (like say 2. Bd5) allows the same capture-check and a new forced mate mentioned in Idea 2 (2…Qxf2+ 3. Bg2 Qg1#).  Moving the bishop to f1 blocks the first rank, but still allows the new forced mate.

Idea 4 – reinforce/defend the attacked square or piece (the h3, f2, and g1 squares).  The are two moves that defend h3 (2. Qa3, and also 2. Qc3 that we looked at under Idea 2) but in both cases black simply captures the queen.  There are three moves that defend f2 (2. Bh3, 2. Qc2, and 2. Qxd4) but again black simply captures and checkmate is back on.  There are zero moves that defend g1 a second time.

Idea 5 – counterattack with an equal or greater threat (of checkmate).  Looking at the EGT chart from earlier we can see that against a checkmate threat, you can only counterattack with a check.  This is a good place to recall my earlier post on counting checks.  Instead of looking at every piece and then searching for each and every check, we can see that only the queen and dark-squared bishop can check the king, which equals a maximum of 14 checks because the bishop normally has 2 (unless one is off the board), and the queen has 12 when she is on the same color square as the target -- that is three checks in each of the four directions the queen can move.  (She only has ten checks when on the opposite color square, because there are only two on each diagonal instead of three.)  In this position the queen has two checks along the 5th rank (2. Qe5+ and 2. Qxf5+), two checks along the c-file (2. Qc7+ and 2. Qc1+), one check on the a3-f8 diagonal (2. Qd6+) and one check along the a7-g1 diagonal (2. Qxd4+).  The bishop can deliver both of its checks (2. Bg5+ and 2. Bd6+), for a grand total of eight checks.

This process has generated eight specific candidate moves, all of which are checks:

The next step is to calculate all eight of the candidate checks.  As I noted in earlier posts about counterattacks we do not know the outcome of the counterattack when we begin calculating, but in this case the position is so extremely bad for white that we can only accept extreme outcomes – a forced checkmate, or forced draw by stalemate or repetition.  We will not be able to capture enough material to reach an equal (or materially-drawn) position, and we won’t be able to construct a fortress.  Even if we could use checks to allow another defense against the checkmate, we’d still be losing.

How to pick which check to calculate first?  They are all forcing, but some are more forcing than the rest meaning they allow white fewer replies.  Quickly counting replies for each check, I see that two of the checks (2. Bg5+ and 2. Qe5+) only offer black one single reply, so we’ll start with those.  I actually do this “reply count” in my head as I’m counting checks to see which checks offer the fewest replies.  Let’s start with 2. Bg5+:

2…Kxg5 (only) and now white must keep delivering checks, hopefully to rid himself of all mobile pieces (the queen, pawn, and bishop) to force stalemate and we have 3. Qe7+ or 3. f4+.  There could be move order issues here so we’ll try both ways.  Let’s start with the queen check first:

3. Qe7+ Kf4 (if either knight captures the queen, 4. f4+ allows white to immobilize his pawn and self-pin his bishop -- stalemate) 4. Qg5+ Ke5 (4. Qd6+? Nxd6 avoids stalemate; if 4…Kxg5? 5. f4+, stalemate).  Here white has five queen checks and one pawn check.  Black cannot capture the queen if his king is on e5 or g5, since it allows f4+ (and stalemate), so the black king must move away from those squares before he can capture the queen.  White of course does not want to allow the black king to get away from those squares.

That eliminates three of white’s checks (all of the queen checks on the f-file), leaving three checks: 5. f4+, 5. Qg7+, and 5. Qe3+.  Since shedding the pawn is an important goal, and the two queen checks seem to allow the king to leave e5, let’s start with:

5. f4+ Kd6 (only) 6. Qe7+ (only check) Nfxe7, and now there is no stalemate because the pawn can move to f5 without a check.  Let’s try white’s two other checks at move 5:

5. Qg7+ Kd6 (5…Kf4 allows 6. Qg5+ leading to draw by repetition), and here white has five checks but since the black king is now not on e5 black can capture the queen.  This only allows white two checks -- one where black cannot capture the queen (6. Qf8+), and one where the capture would put the black king back on e5 (6. Qe5+).  After 6. Qf8+ Nce7 and now both of white’s checks allow black to capture.  That leaves 6. Qe5+ Ke7 (only) 7. Qc5+ (white’s four other checks allow black to capture) Ncd6, and white has no checks and black has avoided the stalemate.  That only leaves one other candidate check at move five:

5. Qe3+ Kd6 (capturing the queen allows the pawn check, and stalemate), and just like in the last variation, again white has five checks but since the black king is not on e5 black can capture the queen.  This only allows two checks -- one where black cannot capture the queen (6. Qf4+), and one where the capture would put the black king back on e5 (6. Qe5+).  We already know from above that 6. Qe5+ Ke7 allows black to avoid the stalemate, so we only need to calculate:  6. Qf4+ Ke7 (looks best; 6…e5?? 7. Qxe5+!; and 6...Kc5 looks good for black too, but white still has lots of check while after 6…Ke7 white very quickly runs out of safe checks) 7. Qg5+ (only safe check) Kf7!, and now white has no more checks.  White can capture the bishop, and perhaps a rook as well, but this is still completely won for black and white still has too much mobility to try for stalemate.

So all of white’s move 5 ideas failed to force checkmate or force a draw, so let’s back up a move and look at white’s other move 3 option, after 1…Kxf4 2. Bg5+ Kxg5 (only) 3. f4+:

3…Kh4! (threatens …Rh3#) 4. Qe7+ (only check) Nfxe7 5. f5 (only) Rh3#

After our first candidate move (2. Bg5+), white cannot force mate and cannot force a draw but since he has evaded checkmate so far and is in a position to capture some black pieces (in the variation after 5. Qe3+), we’ll make this our KOTH.

Only seven more checks to go!!  Deep breath…and moving on to the next most forcing check:

1…Kxf4 2. Qe5+ Kxe5 (only), and here white has three checks but one of them is the most forcing (allowing only one reply), 3. f4+ Kxf4 (only), and we are one step closer to stalemate.  We only need to get rid of our overly-mobile bishop using checks, of which we have two:

If 5. Bd6+ Ke3 and white will soon run out of checks, and will lose.  That leaves us with one last check in the variation:

If 5. Bg5+ Ke5 (forced, 5…Kxg5? is stalemate) 6. Bf6+ Kd6 (forced, 6…Kxd6? is stalemate, and 6…Ke5 repeats) 7. Be7+ Kc7, white just needs to keep checking and now allow the black king to get to c5 or b6, so 8. Bd8+ Kb8 9. Bc7+ Ka7 (only) 10. Bb6+! Kb8 (not 10. Bb8+? Kb6!, and black can get to a light square and escape the checks) 11. Kb8 Bc7+, and although we can’t force the black king to capture our last mobile piece which would force stalemate, repeating the position is black’s only way to not capture the bishop, which is good enough for the draw!

Normally we would note the drawing option, and then continue calculating the other six checks.  But since a draw is really all we can hope for from the starting position, there is no need to keep calculating!  Here is our final chart:

Conclusion:  So this process has shown us that white has several candidate moves to consider in the initial position, and if we follow the path of the most forcing moves first we are able to find the forced draw!  Black has no say in the matter, and his only choice is whether to allow draw by stalemate or repetition!

This is the process you should be able to do mentally:  prioritize the threats, use the five defensive ideas to search for specific candidate moves, calculate each one completely, and then pick the best variation based on the final evaluation.

In the next post we will look at positions where we use EGTs to rearrange our pieces to allow one of the basic defensive ideas (from Idea 1-4).