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Although not a TQG, the simplest and most familiar nondecomposable ternary function is the majority operation M over values a and b, defined by:
- M (a, a, a) = a
- M (a, a, b) = a
- M (a, b, a) = a
- M (a, b, b) = b
- M (b, a, a) = a
- M (b, a, b) = b
- M (b, b, a) = b
- M (b, b, b) = b
Suppose that there were a decomposition M (p, q, r) = F (p, G (q, r)). Then we would have:
- F (a, G (a, a)) = a
- F (a, G (a, b)) = a
- F (a, G (b, a)) = a
- F (a, G (b, b)) = b
- F (b, G (a, a)) = a
- F (b, G (a, b)) = b
- F (b, G (b, a)) = b
- F (b, G (b, b)) = b
Observe:
- From 5 and 6, G (a, a) ≠ G (a, b).
- From 2 and 4, G (a, b) ≠ G (b, b).
- From 1 and 4, G (b, b) ≠ G (a, a).
Thus G (a, a), G (a, b) and G (b, b) must be three distinct values. However there are only two values to choose from, namely a and b, so decomposition fails.