\[ \left \{x'(t)+y'(t)=x(t) y(t),y'(t)+z'(t)=y(t) z(t),x'(t)+z'(t)=x(t) z(t)\right \} \] ✗ Mathematica : cpu = 124.617 (sec), leaf count = 0
DSolve[{Derivative[1][x][t] + Derivative[1][y][t] == x[t]*y[t], Derivative[1][y][t] + Derivative[1][z][t] == y[t]*z[t], Derivative[1][x][t] + Derivative[1][z][t] == x[t]*z[t]},{x[t], y[t], z[t]},t]
, could not solve
DSolve[{Derivative[1][x][t] + Derivative[1][y][t] == x[t]*y[t], Derivative[1][y][t] + Derivative[1][z][t] == y[t]*z[t], Derivative[1][x][t] + Derivative[1][z][t] == x[t]*z[t]}, {x[t], y[t], z[t]}, t]
✓ Maple : cpu = 1.433 (sec), leaf count = 4259
dsolve({diff(x(t),t)+diff(y(t),t) = x(t)*y(t), diff(x(t),t)+diff(z(t),t) = x(t)*z(t), diff(y(t),t)+diff(z(t),t) = y(t)*z(t)})
\[\left [\left \{x \left (t \right ) = -\frac {2}{-2 c_{2}+t}\right \}, \{y \left (t \right ) = x \left (t \right )\}, \left \{z \left (t \right ) = \left (\int -\frac {x \left (t \right )^{2} {\mathrm e}^{-\left (\int x \left (t \right )d t \right )}}{2}d t +c_{1}\right ) {\mathrm e}^{\int x \left (t \right )d t}\right \}\right ]\]