I'm looking for a context-sensitive grammar that describes the following language:
 

L = { ww | w ∈ {a,b}*, |w| ≥ 1} <br> 

I've got problems with the fact that no rules such as X -> ε are allowed and therefore I can't place any nonterminal indicating the "middle" of the word. Is there any trick to the problem?
If you happen to know the answer, please help.

I'm looking for a context-sensitive grammar that describes the following language:

L = { ww | w ∈ {a,b}*, |w| ≥ 1} <br> 

I've got problems with the fact that no rules such as X -> ε are allowed and therefore I can't place any nonterminal indicating the "middle" of the word. Is there any trick to the problem?
If you happen to know the answer, please help.

I'm looking for a context-sensitive grammar that describes the following language:
L = { ww | w ∈ {a,b}*, |w| ≥ 1}
I've got problems with the fact that no rules such as X -> ε are allowed and therefore I can't place any nonterminal indicating the "middle" of the word. Is there any trick to the problem?
If you happen to know the answer, please help.

Thanks, Tobi.

I'm looking for a context-sensitive grammar that describes the following language:

L = { ww | w ∈ {a,b}*, |w| ≥ 1} <br> 

I've got problems with the fact that no rules such as X -> ε are allowed and therefore I can't place any nonterminal indicating the "middle" of the word. Is there any trick to the problem?
If you happen to know the answer, please help.