Special Aronszajn tree
= Special Aronszajn tree
An <Aronszajn tree> that is a union of countably many <tree antichains>. Equivalently, it admits a map into a countable set that is injective on each chain.
= Special Aronszajn tree
An <Aronszajn tree> that is a union of countably many <tree antichains>. Equivalently, it admits a map into a countable set that is injective on each chain.