Descriptive Set Theory provides many deep connections between ordinals and real numbers. Following the precedent set by Ramsey, we are frequently interested in proving coloring theorems for as many ordinals as we can. Following work of Martin, an ordinal is reasonable if there is a well-controlled way to code functions mapping into that ordinal with real numbers. In this talk we will cover some preliminary background, show that ω₁ is reasonable, and use that coding to prove a coloring theorem about ω₁.
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