Skip to main content


Table 1 Symbols of flow expressions (Pimentel et al. 2014)

From: A systematic process for obtaining the behavior of context-sensitive systems

Expression Meaning Example
blank space Sequence (t1 t2), first t1 and then t2
| Alternative (t1 |t2), t1 xor t2
? Optional (t1 t2? t3), first t1 and then t3, or first t1 followed by t2 and t3
* Zero or more times (t1 t2* t3), first t1, then t2 zero or more times, then t3
+ One or more times (t1 t2+), first t1, then t2 one or more times
- Parallelism t1-t2, t1 is executed at the same time as t2.