What is the meaning of lambda here: $$(b+c)^*(a+\lambda)(b+c)^*(a+\lambda)(b+c)^*(a+\lambda)(b+c)^*$$.
I know that lambda is used in the context of NFA?
Let's suppose we break down the expression to:$$(b+c)^*(a+\lambda)(b+c)^*$$
and to:$$(b+c)^*(a+\lambda)(b+c)^*(a+\lambda)(b+c)^*$$
How the above would generate an empty string? Somebody please guide me.
Zulfi.