Other mutation operators select a leaf (external node) of the tree and replace it with a randomly chosen leaf. Another mutation is to select at random a function (internal node) and replace it with another function with the same arity (number of inputs). Hoist mutation randomly chooses a subtree and replaces it with a subtree within itself. Thus hoist mutation is guaranteed to make the child smaller. Leaf and same arity function replacement ensure the child is the same size as the parent. Whereas subtree mutation (in the animation) may, depending upon the function and terminal sets, have a bias to either increase or decrease the tree size. Other subtree based mutations try to carefully control the size of the replacement subtree and thus the size of the child tree.
Other mutation operators select a leaf (external node) of the tree and replace it with a randomly chosen leaf Another mutation is to select at random a function (internal node) and replace it with another function with the same arity (number of inputs) Hoist mutation randomly chooses a subtree and replaces it with a subtree within itself Thus hoist mutation is guaranteed to make the child smaller Leaf and same arity function replacement ensure the child is the same size as the parent Whereas subtree mutation (in the animation) may depending upon the function and terminal sets have a bias to either increase or decrease the tree size Other subtree based mutations try to carefully control the size of the replacement subtree and thus the size of the child tree