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This PR introduces the large semigroups of real numbers under the min / max binary operators.

Comment on lines +215 to +216
associative-max-ℝ : max-ℝ (max-ℝ x y) z = max-ℝ x (max-ℝ y z)
associative-max-ℝ =
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@fredrik-bakke fredrik-bakke Oct 28, 2025

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This is true in any large poset with meets, by the same argument as you demonstrate. Would you be willing to prove it in that generality, if it is not already?

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As a corollary, any large poset has an associated large semigroup under max.

Comment on lines +147 to +151
associative-min-ℝ : min-ℝ (min-ℝ x y) z = min-ℝ x (min-ℝ y z)
associative-min-ℝ =
antisymmetric-leq-ℝ
( min-ℝ (min-ℝ x y) z)
( min-ℝ x (min-ℝ y z))
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Same comment here. this is true by the same proof that you write in all large posets with joins.

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As a corollary, any large poset has an associated large semigroup under min.

@malarbol malarbol marked this pull request as draft October 30, 2025 01:22
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There are weird things going on in the large meet/join semilattices modules: headers are awkwardly asymmetric and don't describe what is actually defined in the module.
I think this should be fixed first; then we can define the min/max semigroup of a meet/join Poset and min/max monoid of a meet/join semilattice.

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2 participants