Questione giuridica chiave
Whether the appellant validly withdrew his cantonal appeal on 17 December 2007.
Decisione estratta
The withdrawal was clear, express, unconditional, and valid; it could not be undone absent proven defects of will.
Motivazione estratta
The wording showed an unequivocal intention to end the proceedings. Later regret and the medical records did not establish incapacity or another will defect with the required degree of probability.