Blocking square: N attackers, N+1 defenders min

Blocking square: N attackers, N+1 defenders min
Compiled by notyetagm

To keep N enemy pieces from occupying a square, the minimum required force is N defenders of that square.

But if -you- want to occupy a square for whatever reason (e.g., <BLOCK> an attack from an enemy line piece) that the opponent controls <N> times, then you must control the square at least <N+1> times.

That is, you are not trying to prevent your opponent from occupying a square; rather, it is one of your -own- pieces that you want to safely occupy a square. In this case <N+1> times is the minimum required and the fact that this number is the minimum means <LOOSENESS>.

27 RxBe7! destroys e7-bishop which controls f6-blocking square
Keres vs Book, 1937
(E06) Catalan, Closed, 5.Nf3, 27 moves, 1-0
31 ... Bxg2!! 32 Rxg2?? White f2-rook must support block on f1
J S Morrison vs Capablanca, 1922
(A46) Queen's Pawn Game, 57 moves, 0-1
16 QxBd6!! Black d6-bishop needed to support block on f8-square
Alekhine vs Koehnlein, 1908
(D05) Queen's Pawn Game, 18 moves, 1-0
28 ... Qd4xRf6! White needs 2 pieces control f1-blocking square
F Handke vs S Atalik, 2000
(E94) King's Indian, Orthodox, 28 moves, 0-1
25 Be6! Black needs b6-queen, g7-bishop to block on h6-square
Gelfand vs Shirov, 1998
(D85) Grunfeld, 39 moves, 1-0
29 RxBe7! Black needs two pieces controlling f8-blocking square
Capablanca vs Spielmann, 1911
(D02) Queen's Pawn Game, 30 moves, 1-0
41 ... a2-a1=Q!! White c3-queen must block f2-h4 on g3-square
Gelfand vs Shirov, 2007
(D85) Grunfeld, 54 moves, 0-1
25 .. Bb7xe4! 26 d3xe4? White d3-pawn can no longer block on d4
Movsesian vs Kasparov, 2000
(B90) Sicilian, Najdorf, 32 moves, 0-1

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