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SUMMARY:Toward deciding the AE-theory of the Sigma02-enumeration degrees -
  Steffen Lempp (University of Wisconsin-Madison)
DTSTART:20220610T133000Z
DTEND:20220610T143000Z
UID:TALK174851@talks.cam.ac.uk
DESCRIPTION:In joint work with Goh\, Kalimullin and Yamaleev\, we present 
 a result toward deciding the AE-theory of the Sigma02-enumeration degrees:
  Ahmad (1989) showed the existence of Ahmad pair in this structure\, namel
 y\, of incomparable degrees a and b such that any degree x<a is <b. On the
  other hand\, we show that her construction cannot be combined with cuppin
 g: No Ahmad pair a and b can join to the top degree 0'.\nI will present th
 e background\, the precise result and a hint at the (finitie-injury!) proo
 f and then state some conjectures on how this result may generalize to 1-p
 oint extensions of finite antichains.
LOCATION:Seminar Room 1\, Newton Institute
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