Source of infection on chessboard

Question

I am looking for the original source of the following well known problem.

Seven unit cells of a 8×8-chessboard are infected. In one time unit, the cells with at least two infected neighbors (having a common side) become infected. Can the infection spread to the whole chessboard?

(It follows since the perimeter of infected part cannot increase.)

This problem appears in "connoisseur's collection" of Peter Winkler, with the following note:

This lovely problem appeared in the Soviet magazine KVANT around 1986, then migrated to Hungary.

I am also interested about Hungary.

P.S. It is found: Moscow mathematical olimpiad 1986, (8-4). Indeed, it appeared in Квант 1986, № 8, с. 57.

I think Laszlo Babai can help about the origin of this problem, because he is from Hungary and this problem is in his list of puzzles. (posted around 2008). — C.F.G, Sep 12 '20 at 06:22
Not helpful for the main wonder, but the Babai list from @C.F.G above begins with a problem whose history I investigated in another question!: MO 105400 — Benjamin Dickman, Sep 12 '20 at 06:58

score 5 · Answer 1 · answered Sep 12 '20 at 09:55

5

The Hungarian connection is in

Gábor Pete: Hogyan gyepesítsünk kockát? [How to make the cube weedy?] Polygon (Szeged) VII:1 (1997), 69-80.
József Balogh and Gábor Pete, Random Disease on the Square Grid (1997)

answered Sep 12 '20 at 09:55

Carlo Beenakker

177,695

Source of infection on chessboard

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