1. In the context of statistics, when the degree of freedom of a statistical model is 0, it means that the model has no freely changeable parameters. This means that the prediction result of the model is completely determined by its input data, without any uncertainty or flexibility. For example, in regression analysis, if the degree of freedom of the model is 0, then the slope and intercept of the model are fixed constants, and the model cannot adapt to any changes in the data.

2. In mechanics, degree of freedom refers to the number of independent coordinates of a mechanical system. The degree of freedom of the system is zero, which means that the system cannot move, forming a geometrically invariant system with no redundant constraints. For example, if you cut grapefruit with a knife and cut it three times along the meridian of the North Pole, you will get six corners. These six angles can be regarded as three pairs, of which only two of the half three angles can be freely selected. Once the two values are determined, the third angle is only determined.