Solution of a Problem of Barendregt on Sensible lambda-Theories
Abstract
<i>H</i> is the theory extending β-conversion by identifying all closed unsolvables. <i>H</i>ω is the closure of this theory under the ω-rule (and β-conversion). A long-standing conjecture of H. Barendregt states that the provable equations of <i>H</i>ω form Π<sub>1</sub><sup>1</sup>-complete set. Here we prove that conjecture.
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