We study the classes of hypersimple and semicomputable
sets as well as their intersection in the weak truth table degrees. We
construct degrees that are not bounded by hypersimple degrees outside any
non-trivial upper cone of Turing degrees and show that the
hypersimple-free c.e. wtt degrees are downwards dense in the c.e. wtt
degrees. Moreover, we consider the sets that are both hypersimple and
semicomputable, characterize them as the (bi-infinite) c.e. cuts of com-
putable orderings of order type omega-plus-omega-star,
and study their wtt degrees.
We show that there are hypersimple degrees that are not bounded by
any hypersimple semicomputable degree, investigate relationships with
the join and look for maximal and minimal elements of some related classes.