An event structure ${\displaystyle (E,\leq ,\#)}$  consists of

• a set ${\displaystyle E}$  of events
• a partial order relation on ${\displaystyle E}$  called causal dependency,
• an irreflexive symmetric relation ${\displaystyle \#}$  called incompatibility (or conflict)

such that

• finite causes: for every event ${\displaystyle e\in E}$ , the set ${\displaystyle [e]=\{f\in E\mid f\leq e\}}$  of predecessors of ${\displaystyle e}$  in ${\displaystyle E}$  is finite
• hereditary conflict: for every events ${\displaystyle d,e,f\in E}$ , if ${\displaystyle d\leq e}$  and ${\displaystyle d\#f}$  then ${\displaystyle e\#f}$ .

• Binary relation
• Mathematical structure

• Winskel, Glynn (1987). "Event Structures" (PDF). Advances in Petri Nets. Lecture Notes in Computer Science. Springer.
• event structure in nLab