In DGS, only a small set of negative elements can be doubled, mainly for emphatic reasons. These are negative particles not (only when occuring with modals), no and negative adverbials never and not.yet. An exemple of each occurence is given below (a-d).
hs hs
a. m-a-x can.not swim can.not
‘Max really cannot swim.’
b. never t-i-m guitar.play never
‘Tim for sure never plays guitar.’
hs hs
c. not.yet ix1 task finish not.yet
‘I have not finished the task yet.’
d. no-no ix2 meat eat no-no
'No, you certainly don't eat meat.'