Regular Operations Union: If L1 and L2 are languages, then L1∪L2={x∣x∈L1 or x∈L2} Concatenation: If L1 and L2 are languages, then L1∘L2={xy∣x∈L1 and y∈L2} Star: If L is a language, then L∗={x1x2...xn∣n≥0 and each xi∈L}