Draw the zero$-$context graph $G_A^0=(V,E)$ for the reaction system $A=(S,A)$ with

$S=\{1,2,3,4\}$ and $A=\{a,b,c,d,e,f\},$ where $a=(\{1\},\{3\},\{2\}),b=(\{2\},\{1\},\{1\}),$

$c=(\{2\},\{3\},\{3\}),d=(\{3\},\{1,2\},\{1,2,4\}),e=(\{4\},\{3\},\{1,2\}),$ and

$f=(\{1,3\},\{2,4\},\{2,3\}).$ Then, redraw it if needed, so that edges do not cross and the

components are clearly visible.