We show that for every nontrivial r.e. wtt-degree a, there are r.e. wtt-degrees b and c incomparable to a such that the infimum of a and b exists but the infimum of a and c fails to exist. This shows in particular that there are no strongly noncappable r.e. wtt-degrees, in contrast to the situation in the r.e. Turing degrees.
"Infima in the Recursively Enumerable Weak Truth Table Degrees." Notre Dame J. Formal Logic 38 (3) 406 - 418, Summer 1997. https://doi.org/10.1305/ndjfl/1039700747