  An algebra $A$ with identity $(a\circ b)\circ c-a\circ(b\circ c)=(a\circ
c)\circ b-a\circ(c\circ b),$ is called right-symmetric. Cohomology and
deformation theory for right-symmetric algebras are developed. Cohomologies of
$gl_n$ and half-Witt algebras $W_n^{rsym}, p=0,$ $W_n^{rsym}({\bf m}), p>0,$
are calculated. In particular, one right-symmetric central extension of
$W_1^{rsym}$ is constructed.
