Tuesday, May 10, 2005

Two days gone

Finished the second day of Concentric Squares using the black rook, black bishop and black queen. I realised that I had overlooked many fork positions yesterday. Today it took me a total of 90 minutes to complete the exercise. I want to confirm this with the other Knights Errant - For the black rook there are 105 fork and 63 skewer positions; for the black bishop 198 fork and 63 skewer positions; for the black queen 0 fork and 63 skewer positions - is this correct?
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Blogger Blue Devil Knight said...

I found some missed forks, skewers, and pins until I was about 4 days into the exercises.

I am starting to really like TCT. I am learning a lot. I have found 2 errors so far (11d#10 and 11c#10). I will be compiling a list of errata for use by the Knights (and for Knights to contribute to).

One problem is that people count things differently. For instance, say you have bishop at d3/king at d5. Queen at f3 forks them, but it is not a 'safe' fork because king to d4 protects the bishop. Some people include these and some don't. I didn't, and MDLM didn't. However, it might be useful to know such 'unsafe' forks because there could be pieces blocking the king from making the protective move.

My long way of saying I'm not sure how many there are.

While working this, I was excited to discover the following:
Queen pins/skewers/forks are the set theoretic intersection of bishop and rook pin/skewer/fork. (Interesection is just the squares they have in common). Knight p/s/f is the set theoretic union of bishop and rook p/s/f. (Union is the set off all squares you can p/s/f for *either* bishop or rook).

I was glad I waited until the third week to do Knight concentric squares. This is because the first knight sight week is very easy (put your finger where the knight can move: it takes like 4 minutes). Doing the knight concentric squares simultaneously was helpful, as it helped solidify the bishop/rook stuff (for the reason mentioned above).

7:10 PM  
Blogger knightwiz said...

I don't know how many pins, skewers and forks are for each position, but that's certainly a good ideia to the them the first time *very* slowly so you don't miss anything.

12:18 AM  

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