Questão jurídica principal
Whether the signed final invoice constituted an acknowledgement of debt under Art. 82 LP.
Decisão extraída
Yes. The signed invoice, showing a determinable amount due and signed without reservation, qualified as an acknowledgement of debt.
Fundamentação extraída
A privately signed document need only clearly show the debtor's unconditional commitment to pay a determined or readily determinable sum. The invoice's wording, signature, and later partial payment supported that conclusion.