North American beaver beaver may dwell in a bank burrow and bank lodge with an underwater entrance. The beaver dam is constructed using branches from trees the beavers cut down, as well as rocks, grass, and mud. The inner bark, twigs, shoots, and leaves of such trees are also an important part of the beaver's diet. The trees are cut down using their strong incisor teeth. Their front paws are used for digging and carrying and placing materials. The sound of running water dictates when and where a beaver builds its dam. Besides providing a safe home for the beaver, beaver ponds also
Busy beaver uncomputable. If "S"("n") was computable, then we could solve the blank tape halting problem simply by running any given Turing machine with "n" states for "S"("n") steps; if it has still not halted, it never will. So, since the blank tape halting problem is not computable, it follows that "S"("n") must likewise be uncomputable. For any model of computation there exist simple analogs of the busy beaver. For example, the generalization to Turing machines with "n" states and "m" symbols defines the following generalized busy beaver functions: For example, the longest-running 3-state 3-symbol machine found so far runs steps before