1. The problem asks to write down the lower bound for the length. 2. In mathematics, a lower bound for a length means the smallest possible value that length can take. 3. If the length is represented by a variable, say $L$, then the lower bound is a value $m$ such that $L \geq m$ for all valid lengths. 4. For example, if the length cannot be negative, the natural lower bound is $0$. 5. Without additional context or constraints, the general lower bound for length is $0$ because length cannot be negative. 6. Therefore, the lower bound for the length is: $$L \geq 0$$ This means the length is always greater than or equal to zero.