Invalid signature. The validity condition of the letter of commitment: 1, and it has the right to dispose of its own rights and interests; 2. The promisor must be mentally mature, with normal age and mental state, and be able to understand what he has done. 3. It must be the true intention of the promisor. 4. It must be a promise made by the promisor in a realistic state. 5. Commitment must occur before the behavior results. 6. Commitment must be understood through behavior. 7. The act shall not exceed the scope promised by the promisor. When a contract is deemed invalid, it should be distinguished from contracts with pending validity and revocable contracts. A contract with undetermined validity is a contract with undetermined validity at that time and needs ratification. If it is approved, it will be effective. If it fails to approve or refuses to approve within the approval period, it is invalid. Legal basis: the effect of false statement and concealment in Article 146 of the Civil Code. A civil juristic act with false meaning made by the actor and the counterpart is invalid.

The validity of a concealed civil juristic act with false intention shall be handled in accordance with relevant laws and regulations.

Article 147 The validity of a civil juristic act based on a major misunderstanding. For a civil juristic act based on gross misunderstanding, the actor has the right to request the people's court or an arbitration institution to cancel it.

Article 148 If a party commits a civil juristic act against its true meaning by fraudulent means, the defrauded party has the right to request a people's court or an arbitration institution to cancel it.

Article 149 If a third party commits a civil legal act against its true meaning, and the other party knows or should know about the act, the aggrieved party has the right to request the people's court or an arbitration institution to cancel it.

Article 150 If one party or a third party coerces the other party to carry out a civil juristic act against its true meaning, the coerced party has the right to request the people's court or an arbitration institution to cancel it.

Article 151 Validity of Civil Legal Acts If a party in obviously unfair takes advantage of the other party's danger and lack of judgment, resulting in the establishment of a obviously unfair, the injured party has the right to request the people's court or an arbitration institution to cancel it.