Exchange-Sac evaluation

  • #1

    Hi all,

    I love positional exchange sacs, but I have to admit I'm always nervous when the opportunity comes up for me, and often settle for a more timid positional move. In the below game, I think I made a pretty good one, but I'd like some other analysis/opinions.

    My computer likes the move I chose 23... Rxb4, but slightly prefers Rbb8. I chose to make the sac because it gave me a very clear plan -- push the connected pawns and try for a squeeze play. What would you have played?

  • #2

    Thanks, Powerlevel, I appreciate your taking a look.

    I didn't feel the exchange was forced. Rb8 looks very playable, though not as interesting of course!

  • #3

    Looks like a textbook example of these exchange sacs. As you say it gives you clear play and white is the one who has to be careful, so very certainly a good move Smile

  • #4

    Definitely a good one! I would always play the exchange sac here (I love playing them too), you get a minor piece and a pawn for the exchange, plus two connected passers on the side of the board where you are stronger. I think the main thing is that White already has a "weakness" on e4 and his pieces are uncoordinated - by giving him this other thing to deal with his position just collapses under the pressure.

  • #5

    Good exchange sac for all the reasons mentioned.  One thing I would say though, going through the game, I noticed you kept blocking your pawns with pieces. If I'm playing black, those pawns are going to move pretty quickly as long as they aren't hanging.  Your position was so great that just about anything worked.

  • #6

    Exchange sacrifices just aren't in my locker, would have to be very obvious for me to even consider it.

    Any good reference materials for them, or is it an experience/judgement thing mainly?

    Perhaps playing through master games when they have done them is good?

  • #7

    Scott, for a long time, I was in your boat but now I've learned to really like exchange sacs.  I don't play much OTB chess but in speed I will sac exchanges often.  For me, it's an experience/judgement thing.  I really like imbalanced poisitions and exchange sacs fit the bill.  There are so many things to consider when doing it but for me it's usually about piece play.  After the sac, do I get to move freely?  Do I now have a piece that is very dominant?  Are they bottled up somehow?  Do they have limited counterplay after the sac?  There's a lot more to consider though, hence why I consider it a feel thing.  But I suppose you could add up all your pluses and see if it outweighs the negatives.

    In the above game, it's pretty clear after the sac that black has two connected pawns that probably can't be stopped.  As someone mentioned earlier, the rook is such a poor defender in such positions so unless white somehow creates mating threats, black's game is simple.

  • #8

    Thanks.

  • #9

    Bonsey,

    I had to be careful about pushing them too far right away. For example, an early push to b3 allowed White's knight to go to c3 blocking the c pawn and covering b1. At the same time, an early push to c3 allowed a return of material via Nxc3, bxc3, Rxc3, and the pawns are gone. I think tying him down further was a good idea.

  • #10

    I like it because white is forced to give up his "good" bishop of his bishop pair and the creation of


    the two connected passed pawns, looks like a tough day at the office for white. Here is a game that the exchange-sac brings down the curtain !

  • #11
    JamieKowalski wrote:

    Bonsey,

    I had to be careful about pushing them too far right away. For example, an early push to b3 allowed White's knight to go to c3 blocking the c pawn and covering b1. At the same time, an early push to c3 allowed a return of material via Nxc3, bxc3, Rxc3, and the pawns are gone. I think tying him down further was a good idea."

     

    Yes you are correct in thinking about these things and given how great your position is, you can do most anything that doesn't mess it up.  I'm playing 26...c5 all day.  It protects your b-pawn and threatens the pawn roller.  I'm not blocking play with Bc4, but maybe that is a stylistic thing.  Once again, your position is so strong that you can do just about anything that doesn't hang any of the pawns. 

  • #12

    Post

  • #13

    I think the exchange sacrifice was a mistake in this case. How would you meet a white f4 instead of the weaker Qa1? Black has a comfortable advantage after Rbb8 and start working on re-routing the offside knight. What happens after Rxb4 is too unclear compared to this clear advantageous alternaltive.

    Black has a number of good plans here revolving around the square b3 and rerouting the offside knight. It's harder for white to find good roles for his pieces, especially the bishop.

  • #14

    Too quick post! I had my tactics messed up and it turns out white is fine, he can just exchange his bishop for the knight and it's pretty much a dead draw. I have a blind spot for giving up the bishop pair sometimes and forgot to consider the move.

    I guess the exchange sac is a good try, and the only way to press for an advantage then, but I still think it's unclear where it's headed with best play.

  • #15

    Steinar wrote:

    I think the exchange sacrifice was a mistake in this case. How would you meet a white f4 instead of the weaker Qa1? Black has a comfortable advantage after Rbb8 and start working on re-routing the offside knight. What happens after Rxb4 is too unclear compared to this clear advantageous alternaltive.

    Black has a number of good plans here revolving around the square b3 and rerouting the offside knight. It's harder for white to find good roles for his pieces, especially the bishop.

    _____________________________________________________________________________________________

    Thank you Steinar. The silicone beast is right again with 23...Rbb8.

    You saved me from writing a long post. My obsession with this game has always been being able to get at the "truth" of the position. To me it is an elixir. Well done Steinar!

  • #16
    Steinar wrote:

    Too quick post! I had my tactics messed up and it turns out white is fine, he can just exchange his bishop for the knight and it's pretty much a dead draw. I have a blind spot for giving up the bishop pair sometimes and forgot to consider the move.

    I guess the exchange sac is a good try, and the only way to press for an advantage then, but I still think it's unclear where it's headed with best play.

    Seems very strong players (Masters) definately will not part with those Bishop Pairs until they have calculated your Demise ! Frown That is one of the reasons i like this exchange sack because it forces white to give up the "good" bishop in his pair. But as you said even with best play as far as one can calculate things remain unclear.

  • #17
    top2pr wrote:

    Well since you didn't bother to (click: board coordinates) I wont bother to run it.

    It keeps the riff-raff out.

  • #18

    @Steinar & transpo,

    As I mentioned, my engine (Critter) did prefer Rbb8, but not by much. It still evaluated my move as about a quarter-pawn advantage to Black after given a very long think (around 29 plies, I believe). The difference was negligable between the two choices. I might do a position shoot-out in Fritz to see what happens down the road in some of these variations. 

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