Ambiguous Grammar demostration exercise
An example is the word $aabbab$.

We can either create it like this
$$S \rightarrow aT \rightarrow aaTT \rightarrow
 aabST \rightarrow aabbRT \rightarrow aabbaT \rightarrow aabbab.$$
Or like this
$$S \rightarrow aT \rightarrow aaTT \rightarrow
aabT \rightarrow aabbS \rightarrow aabbaT \rightarrow aabbab.$$