<s>
In	O
mathematics	O
and	O
computer	B-General_Concept
science	I-General_Concept
,	O
an	O
event	B-General_Concept
structure	I-General_Concept
represents	O
a	O
set	O
of	O
events	O
,	O
some	O
of	O
which	O
can	O
only	O
be	O
performed	O
after	O
another	O
(	O
there	O
is	O
a	O
dependency	O
between	O
the	O
events	O
)	O
and	O
some	O
of	O
which	O
might	O
not	O
be	O
performed	O
together	O
(	O
there	O
is	O
a	O
conflict	O
between	O
the	O
events	O
)	O
.	O
</s>
