User Profile: agb2002

agb2002
Member since Jun-28-08 · Last seen May-22-13

I'm an applied mathematician who lives in the south east of Spain. I'm not rated.
My favorite players are those considered the best endgame artists of all time: Lasker, Rubinstein, Capablanca, Smyslov and Fischer. I also tend to prefer the strategists (Botvinnik, Karpov, Kramnik) and the universal style players (Spassky, Anand) to the tacticians. However, I like accurate chess regardless of the players and styles.
My approach to the puzzles is similar to that of David Zechiel (User: dzechiel): I first write the variations I find in a reasonable amount of time (using the puzzle diagram only) and post them before watching the game or other's comments. Then I have a look at them and try to be critical with my work. I apply the touch-move rule to my posts (see Unzicker vs Fischer, 1960). I hope to improve my tactical vision this way.
Often I cannot even spend a couple of minutes looking at the diagram (work, family, other interests, etc.) so I try to blind solve it along several breaks. My first attempt was R Vera vs S Garcia-Martinez, 2001 and although the variations I found were not very deep I felt quite satisfied with the experience.
I became interested in puzzle Elo ratings after trying to find a way of measuring my progress with these exercises. However, computing just rough estimates of the Elo rating of a given puzzle is a difficult problem. Some strategies to accomplish this are:
I. Machine estimates. This method is pursued by User: MostlyAverageJoe so you should refer to his forum for further details.
II. FIDE Elo distribution. This method assumes that the following more or less reasonable assumptions hold:
1) The puzzle kibitzer Elo distribution is close enough to that of FIDE rated players.
2) A player with Elo x is a good representative of the players belonging to the Elo interval [x-25, x+24].
3) Kibitzers are objective and only claim the point when they really worked out the complete solution.
I have approximated the FIDE Elo distribution with this table (source http://www.fide.com, Dec 31 2008):
__A_ | __B_ | __C_ | __D__ | __E__ | ___F___
1325 | 1300 | 1349 | 99209 | ____0 | 100.0000
1375 | 1350 | 1399 | 99209 | ____0 | 100.0000
1425 | 1400 | 1449 | 99209 | __185 | 100.0000
1475 | 1450 | 1499 | 99024 | __373 | _99.8135
1525 | 1500 | 1549 | 98651 | __558 | _99.4376
1575 | 1550 | 1599 | 98093 | __850 | _98.8751
1625 | 1600 | 1649 | 97243 | _1286 | _98.0183
1675 | 1650 | 1699 | 95957 | _1851 | _96.7221
1725 | 1700 | 1749 | 94106 | _2594 | _94.8563
1775 | 1750 | 1799 | 91512 | _3511 | _92.2416
1825 | 1800 | 1849 | 88001 | _4677 | _88.7026
1875 | 1850 | 1899 | 83324 | _5879 | _83.9883
1925 | 1900 | 1949 | 77445 | _7053 | _78.0625
1975 | 1950 | 1999 | 70392 | _8236 | _70.9532
2025 | 2000 | 2049 | 62156 | 10602 | _62.6516
2075 | 2050 | 2099 | 51554 | 11189 | _51.9650
2125 | 2100 | 2149 | 40365 | 10541 | _40.6868
2175 | 2150 | 2199 | 29824 | _8745 | _30.0618
2225 | 2200 | 2249 | 21079 | _7531 | _21.2471
2275 | 2250 | 2299 | 13548 | _5311 | _13.6560
2325 | 2300 | 2349 | _8237 | _3358 | __8.3027
2375 | 2350 | 2399 | _4879 | _1993 | __4.9179
2425 | 2400 | 2449 | _2886 | _1367 | __2.9090
2475 | 2450 | 2499 | _1519 | __643 | __1.5311
2525 | 2500 | 2549 | __876 | __451 | __0.8830
2575 | 2550 | 2599 | __425 | __238 | __0.4284
2625 | 2600 | 2649 | __187 | __109 | __0.1885
2675 | 2650 | 2699 | ___78 | ___46 | __0.0786
2725 | 2700 | 2749 | ___32 | ___20 | __0.0323
2775 | 2750 | 2799 | ___12 | ___11 | __0.0121
2825 | 2800 | 2849 | ____1 | ____1 | __0.0010
2875 | 2850 | 2899 | ____0 | ____0 | __0.0000
where column A is the Elo representative of the class of players determined by columns B and C, column D is the amount of players stronger or equal, column E is the amount of players in the corresponding class and column F is the percentage of players stronger or equal.
Now, if, for example, 70% of us solved completely the puzzle, I would rate it at Elo 1975 or better, between 1950 and 1999 points.
Unfortunately, not all of us publish (an excerpt of) our findings to 'prove' that we got the solution (or a terrible embarrassment...). This translates into many computational problems: from strong bias (as pointed out by John Spouge, see agb2002 chessforum) to such lack of resolution that assessing the more difficult puzzles becomes impossible (see agb2002 chessforum).
III. Puzzle characteristics. There are some features in every puzzle that can be used as metrics to evaluate its difficulty, for example, the type and number of tactical motifs, the number and depth of variations, the type and amount of material still on board, etc. For example, many players will solve the following puzzle immediately (White to move, Lasker's Manual of Chess, p. 116):

click for larger view
However, the next puzzle is considerably more difficult in spite of containing practically the same tactical motifs (White to move, Lasker's Manual of Chess, p. 119):

click for larger view
Once having collected a sufficient number of puzzles with their metrics and Elo evaluation (perhaps using method I) it might be possible to fit a several variable function in which the independent variables are the metrics and the dependent variable is the given Elo rating.
IV. Post characteristics. We can try to use some metrics from the posts to estimate its rating. These metrics would include:
1. CG assigned stars.
2. Posts issued on the puzzle's day.
3. Posts recognizing failure.
4. Plies to reach a clear decision, draw included.
5. MostlyAverageJoe's rating (thanks MAJ!).
6. Posts claiming (or implying) it was (too) easy.
7. Posts complaining (or implying) it was (too) difficult.
Once having collected enough data (from at least 30 puzzles) we would try to find the most suitable fitting model f:
rating = f(x1, ..., x7)
xi being the above variables, not necessarily all included in the model. For example, it could be as simple as
rating = 1200 + 100*plies
As a curiosity, this is a VBA function for the best fitting model I've found to date using the CG stars (cgs) as the only predictor variable (N = 181, R² = 0.688, asymptotic standard errors five times -at least- smaller that the corresponding coefficients):
Function MAJ_Rating(ByVal cgs As Double) As Double
Const a As Double = 861.15488885
Const b As Double = -0.555156265
Const c As Double = 0.156127404
Const d As Double = -0.015186844
MAJ_Rating = a / (1 + cgs * (b + cgs * (c + cgs * d)))
End Function

Comments are welcome.

>> Click here to see agb2002's game collections.

   agb2002 has kibitzed 2352 times to chessgames [more...]

   May-22-13 I Berezovsky vs V Rusel, 1984

agb2002: The material is identical. Black threatens 11... fxg5 and 11... Bxh6. A royal fork on f7 would be possible if the rook on f8 disappeared. Therefore, 11.Qf7: A) 11... Rxf7 12.Nxf7+ Kg8 13.Nxd8 A.1) 13... Bxh6 14.Nxb7 Na6 15.Na5 + - [R+P vs B] . A.2) 13... b6 14.Bxg7 Kxg7 15.e3 ...

   May-21-13 Korchnoi vs I Krush, 2007

agb2002: The material is identical. White threatens 28.Bd3 and 29.Bc4 (28... Rxd3 29.Qf8#). The first idea that comes to mind is 27... Rxd2 to win two pieces for a rook. However, this loses miserably to 28.Qf8#. A change in the move order yields 27... Qxe4: A) 28.Nxe4 Rd1+ 29.Rf1 Rxf1#. ...

   May-20-13 F J Moyano Morales vs C Merlo, 1967

agb2002: White is one knight down. Black threatens 20... Rxd2. Pattern recognition quickly finds a mate in two: 20.Qg5+ Rxg5 21.Rxg5#.

   May-19-13 Yifan Hou vs Lahno, 2012

agb2002: White has the bishop pair for a bishop and a knight. Black threatens 38... Qxc1, 38... Qxa4 and 38... Qh5+ trading queens. The moves I would initially consider are 38.gxf6+, 38.g6 and 38.Qxg7. In the case of 38.gxf6+ gxf6 (38... Kxf6 39.Qh4+ g5 40.Qxg5#) 39.Bh6 Qh5+ 40.Kg3 Nb8 ...

   May-18-13 Staunton vs Von Der Lasa, 1853

agb2002: <Abdel Irada: <agb2002: Black is one pawn.> I thought this site was about chess, not Zen philosophy. ∞> Then, what's the meaning of the infinity symbol you add at the end of your posts? I'm intrigued...

   May-17-13 Fischer vs W Beach, 1963

agb2002: White is one pawn down. Black threatens 21... dxe4 and is about to castle (assuming it still is legal). The black bishop protects the knight, which covers the defenseless rook on b8. This suggests 21.Bh6: A) 21... Bxh6 22.Qxe5 A.1) 22... O-O 23.Nf6+ Kf7 24.Nd7 wins the exchange ...

   May-16-13 D Edelman vs J Curdo, 1983

agb2002: Black has the bishop pair for a bishop and a knight. White seems to try to simplify the game by removing the bishop on b6. The white bishop is momentarily pinned. This suggests 18... Nxf3+ (18... Rxe3 19.Nxb6) 19.gxf3 Qg5+: A) 20.Kf2 Rxf3+ 21.Kxf3 (21.Ke2 Rexe3+ 22.Qxe3 Qxe3#) 21...

   May-15-13 N Aggelis vs A Heimann, 2012

agb2002: <Patriot: Hmm...31.Qe7 Nxh3+ 32.Kf1? Qxd5 wins for black. 31.Qd6 is something I never considered here.> And I missed in my line C for 31.Qe7 the obvious 33... Kh7. Curious.

   May-14-13 Anand vs Karjakin, 2013

agb2002: However, we cannot discard a possible fifth victory.

   May-14-13 T Hickendorff vs R Van Bokhorst, 2005

agb2002: Black is one bishop and one pawn down. White threatens the pawn on e5. The rook on a2 is momentarily safe due to the discovered check with royal fork ... Nc3+. This detail leads to consider 25... Ra1+, and the white king doesn't have the escape square b3 so gets mated: 26.Kxa1 Nc3+

indicates a reply to the comment.

Calculo, luego existo

< Earlier Kibitzing · PAGE 7 OF 7 · Later Kibitzing>
Mar-28-11		Patriot: <agb2002> <Have you considered a different approach instead of Candidate Moves (CM)? Valeri Beim in his 'How to Calculate Chess Tactics' calls it Logical Analysis and I prefer it over CM because the former is less mechanical and promotes a deeper understanding of the position. I suspect it was also Capablanca's method because it would explain facts like being able to crush masters at blitz even giving them odds of 1-5 minutes.> That is very interesting. I will likely ask my instructor for his opinion. I also wonder if this is a good approach for my level. When I was rated around 1300 it certainly wouldn't have helped because I had to be missing a lot of basic tactics to be at that level. Silman's books helped to a point but studying "Silman's thinking technique" was not the best approach. What good is knowing positional concepts if you don't see tactics? My instructor has suggested that I get Silman's newest revised book because I'm now at a level where it would help. Silman's approach may be similar to what you're suggesting and I do plan to get his book. One problem I faced was that I tried to apply Silman's approach in G/30 which turned out to be disastrous because I would spend 10-15 minutes trying to understand or create imbalances! It may have contributed to poor time management that I'm facing now. This is why I am playing a lot of 2 minute games (+5 sec increment). I'm trying to gear myself toward proper pace and develop a better awareness of time. It should help me to become quicker at spotting basic safety issues and develop a better sense of when to play fast (non-critical positions) and when to play slow (critical positions). It seems that "pace" is the most important thing in chess because it determines how one should analyze a position. This kind of practice is probably the single most important thing I can do right now to improve.

Mar-31-11		Patriot: <agb2002> <However, my experience is the contrary: it doesn't matter the activity (lifting weights, playing piano, programming computers, devising algorithms, learning foreign languages, etc.) you must master the technique before you can push your skills, including performance speed, to their limits (so you can already face heavier loads, more complex studios, more reliable & quicker software, optimized algorithms, hold a conversation, etc.).> Sorry, I don't understand what you mean by "technique". Do you mean I should learn the technique of "Logical Analysis" before trying to improve my pace, tactical vision, etc.? Thanks!

Jul-03-11		johnlspouge: Hola, <Antonio>. Thanks for the suggestion about installing software on my cellphone. Unfortunately, you are talking to a determined Luddite. My ancient cellphone barely remembers how to make phone calls ;>) I appreciate your computer analysis on Bxe2. I find that I am enjoying the POTD again - very civilized and productive - you might find me hanging around more than I thought :) Keep well (and keep doing pushups).

Jul-06-11		Patriot: Thanks Antonio for your input!

Aug-24-11		morfishine: Your analysis on todays Puzzle (Wednesday 8-24) was excellent, to say the least. I enjoyed every word of it. Thanks, Morf

Dec-20-11		CHESSTTCAMPS: <That's why I routinelly include imminent threats in the preliminaries to my solution. It's a simple method to create a habit I can use in real games.> Sorry for the late response - I hadn't been monitoring my forum lately. I had noticed this feature of your posts and have recently made a point of adding this good habit to my write-ups when it is particularly relevant to my thought process. <By the way, the machines we sent to Ohio last year have shown such performance that a large company specializing in industrial plants became interested in producing them for the American market. So, it is very likely that I'll become a temporary neighbor of Wisconsin early next year to train their engineers on the calculation (sizing/rating) of these machines.> Congratulations on your success in this endeavor and I hope you enjoy your stay in Wisconsin. I was just writing a Christmas letter to an old professional client who now works in neighboring Minnesota. If you are up there in the winter, I hope the weather is kind to you. Speaking of fine Spanish products, I must tell you that the Clementines we've been receiving from Spain this autumn are perhaps the best citrus fruit I've ever tasted.

Dec-26-11		CHESSTTCAMPS: <I also tried to guess the opening from which the position came, to accumulate some knowledge about what tactics one can expect from what openings but I forgot that habit.> Another good idea, which I may pursue at least occasionally. <If you want to impress your friends you should consider three Spanish products:...> All of these suggestions sound wonderful, but I'm keeping to a fairly tight budget right now. Boxes of about 20 clementines sometimes sell for as low as $3.99 at Giant food stores, a terrific bargain. Later in the season, when the quality is not so good, the price sometimes rises to $10 or more - go figure. I hope that you and your family enjoyed a wonderful Christmas.

Jan-01-12		CHESSTTCAMPS: <Yes, we experience similar price increases here. ...> I take note of your point about Morroccan fruit being held to lower standards. Giant Foods has carried both Spanish and Morroccan clementines in recent years, the latter usually starting in January and later. Usually, both are delicious. I think that Giant is a reputable outfit and they would take care that their label means what it says. In any case, if there are serious doubts about the source, I think that consumer watchdogs would raise the issue loudly and clearly. <Similarly, avoid some Italian "products",....> This is interesting, something I was not aware of. I am a regular consumer of olive oil. <Thank you, I wish you the same for you and your family and a good New Year.> Thanks, Happy New Year to you, too.

Feb-03-12		Patriot: <agb2002> <Hello Patriot, how is the new year treating you? Hope everything is ok with you and your family.> My apologies for not responding to you sooner! I really thought I had responded back and just noticed I haven't! Everything is going well with me and my family. I appreciate you asking and I hope all is well with you! Keep up the amazing work on the puzzles! Take care.

Apr-10-12		johnlspouge: Hola, <Antonio>. Thanks for "dropping by". I hope you and your family are well. I looked at the reviews of Penrose's "The Road to Reality", which I have not read, and I am daunted. Do I want to spend the time and effort required to understand the book? I therefore turn your question back to you: what did you think of the book? Be judicious in your answer, please ;>) All the best, John

Apr-12-12		johnlspouge: Hi, Antonio. Your review link http://www.ams.org/notices/200606/r... was good enough. The book is a must-read. I will let you know how it goes. Thanks for thinking of me :) All the best, John

Apr-15-12		quantum.conscious: hi <antonio> , thanks for your posts about roger penrose books. i found them very interesting.

Apr-17-12		agb2002: <quantum.conscious: hi <antonio> , thanks for your posts about roger penrose books. i found them very interesting.> Thank you! It seems that the interest on Penrose's Road is skyrocketing: I can count three now which means a tremendous increase of 50%! ;-)

May-11-12		ketchuplover: Go Boris!!!!!!!

Jun-11-12		LoveThatJoker: <agb2002> Hi! I'm sending you this note to firstly thank you for your kind and objective acknowledgment on M Beinoras vs H Salo, 2009. I made sure to post my original thank you there! I had a fellow CG full member, <AlienMath> post a question on High-Mathematics on my forum that I cannot assist on elucidating on, due to the fact that I am not a trained Mathematician. The question is located directly on this link LoveThatJoker chessforum. Any help on the elucidation of the concepts of both the Goldberg conjecture and the Riemann hypothesis would be genuinely appreciated. Thank you! LTJ

Jun-12-12		LoveThatJoker: <agb2002> Thank you for the kind reply on my forum! LTJ

Jun-14-12		LoveThatJoker: <agb2002> Do you have any idea who this is? Look at Book 3 here http://chessbase.com/newsdetail.asp.... I will give you anyone you want in exchange for this one. LTJ

Jun-15-12		LoveThatJoker: <agb2002> Thank you for getting back to me on that! LTJ

Jul-22-12		Patriot: Hi <agb2002>! <I agree. I still have to rethink my move selection algorithm.> Usually you latch right on to the correct move. Do you consider other candidates or do you usually only post the principle candidate after analysis? For example in today's puzzle, I thought 22.Bh6 was a good candidate and 22.Nb5 was interesting, although I didn't post anything about it initially. 22.Rxf6 was the first move I saw but I didn't see the Kh1, Rg1 idea and thought it was unnecessarily complicated. By the way, good job on the POTD!

Oct-01-12		morfishine: Hello <abg2002>! Nice write-up in the Sunday POTD! I only noticed <25...Bxe4> immediately after posting 25.Rxb4 <25...axb4>. I briefly considered deleting my post then adding this as a possible improvement but decided to leave these separate. I'm a bit surprised there wasn't more discussion on <25...Bxe4>

Nov-14-12		Patriot: Hi <agb2002>! Good job on your win! I read your comment about losing the exchange before going over your game so when you played 20.Rae1 I figured the rook on f1 was going to be the piece. I've lost the exchange quite a few times like this so I'm very suspicious about moves that trap the rook. I had a question about 11.Nxe7+. What prompted you to play this? That knight is a real thorn thanks to 9...b6?. I wouldn't recommend trading it until forced to do so since the bishop isn't going anywhere. That's similar to what Dan told me once when I captured a pinned piece. He said "You should almost never capture unless they threaten to break the pin or capture the pinning piece, for example." By not capturing, you have time to build your position further while he is left dealing with the situation. It really looks like you did have a bad day though--we all have them! I just thought I'd mention the knight capture though because that move really stood out with me. But it's probably something you wouldn't have done on any other day! Thanks for sharing!

Nov-25-12		ShahMaat: ...no comment.New guy on the block.I enjoy the dialogue between the users.I thank you all,and look forward to crossing swords with you!Unrated old fart.

Jan-18-13		Patriot: Hi <agb2002>! I loaded your game into Fritz and followed it. You played a nice game against Houdini! On move 35 (white to play), how did you evaluate the position: click for larger view I might think black is a little better, and Houdini agrees after 22-ply. You said 35.Bf1 was better but at 22-ply, it agrees with you! <35.Ba6>

Jan-19-13		Patriot: Hi <agb2002>! <Perhaps the note below the players showing the engine which performed the analysis misled you.> Yes this is exactly what happened--I completely misread that (sorry). Your plan, having the outside passed pawn, is a good one. Nice game!

Mar-03-13		Jimfromprovidence: Thanks for the constructive feedback concerning Saturday's puzzle. Jim

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