Fish
The basic fish family: X-Wing, Swordfish and Jellyfish balance one digit across N base houses and N cover houses.
X-Wing
A two-row or two-column fish construction.
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Swordfish
A three-row or three-column fish construction.
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Jellyfish
A four-row or four-column fish construction.
Continue ReadingBase houses, cover houses, one digit
A basic fish picks one digit, N base houses (rows or columns) and N cover houses (the other orientation) such that every remaining candidate of the digit inside the base lies inside the cover. The N base houses must place the digit N times — once each — so every candidate in the cover outside the base is eliminated.
X-Wing (N = 2), Swordfish (N = 3) and Jellyfish (N = 4) are the same rule at growing sizes; the larger fish are rarer rather than logically deeper. Pointing and Claiming can be read as size-1 fish, though they are taught earlier as box–line reduction. Finned, Franken and mutant fish extend the same accounting with fins or mixed-house covers.