  The Deligne-Simpson problem (DSP) (resp. the weak DSP) is formulated like
this: {\em give necessary and sufficient conditions for the choice of the
conjugacy classes $C_j\subset GL(n,{\bf C})$ or $c_j\subset gl(n,{\bf C})$ so
that there exist irreducible (resp. with trivial centralizer) $(p+1)$-tuples of
matrices $M_j\in C_j$ or $A_j\in c_j$ satisfying the equality $M_1...
M_{p+1}=I$ or $A_1+... +A_{p+1}=0$}. The matrices $M_j$ and $A_j$ are
interpreted as monodromy operators of regular linear systems and as
matrices-residua of Fuchsian ones on Riemann's sphere. The present paper offers
a survey of the results known up to now concerning the DSP.
