How do you read this math symbol?

[zeion]

Hi,

I'm studying computation theory and this symbol that looks like a capital A without the middle bar is used to denote the empty string.

What is it called?
Thanks.

EDIT: Looks like its a capital lambda?

 

[Hurkyl]

Capital lambda ($\Lambda$) sounds right. I have seen it used to denote the null string.

 

[wisvuze]

For future reference:

http://detexify.kirelabs.org/classify.html

is a good site where you can draw a symbol and it will identify it for you ( or try to )

 

[zeion]

For future reference:

http://detexify.kirelabs.org/classify.html

is a good site where you can draw a symbol and it will identify it for you ( or try to )

Seems useful, thanks!