Regular expressions clarification

Question

I'm currently using the TheoryOfComputation book by Maheshwari and Smid to study regular expressions. In the book, examples were given as:

The language

$$\{w \in \{0,1\}^* : \text{the length of } w \text{ is even}\}$$

is described by the regular expression

$$((0 ∪ 1)(0 ∪ 1))^*$$

Some people in class said that it can also be written as

$$((0 + 1)(0 + 1))^*$$

Is this true?

I think the $\cup$ and $+$ are just different signs representing the same operation. See Boolean Arithmetic — packetpacket, Jul 30 '18 at 19:15

score 2 · Accepted Answer · answered Jul 30 '18 at 19:15

2

Yes. $+$ and $\cup$ both denote the union operation.

answered Jul 30 '18 at 19:15

Hans Hüttel

Thank you for the clarification, is word and string mean the same thing also? – Jae Jul 30 '18 at 20:27
Yes, this is another example of how terminology and notation may vary. – Hans Hüttel Jul 30 '18 at 20:43

1 Answers1