Recursively enumerable $bw$-degrees

For every nonrecursive recursively enumerable (r.e.) set $A$ are constructed bw-incomparable r.e. sets $B_i$, $i\in N$, such that $B_i<{}_{bw}A$ and $B_i\equiv{}_wA$. The existence of an infinite antichain of r.e. $m$-degrees in every nonrecursive r.e. $bw$-degree, and also that of an r.e. set $A$ with the property $A^n<A^{n+1}$, $n\in N$, is proved.