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> SELECT (SomeType, 1)

This cannot be the case if you call each thing a 'set'. Unless `(a, b)` calculates the cross product, there is no meaningful non-arbitrary way to assign each element of a to an element of b. That would depend on an ordering, which makes it not a set to everyone but a marketing dept somewhere.

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`(a, b)` is a cross-product, just like "SELECT * FROM a, b"

They're saying that both of those expressions are valid, not equivalent.

SELECT count(star) FROM table

and

SELECT star FROM table

Are both valid, not equivalent.

Furthermore, listing any kind of set depends on some ordering, be it random.

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