Holland's schema theorem
where  is the order of the schema,  is the length of the code,  is the probability of mutation and  is the probability of crossover. So a schema with a shorter defining length  is less likely to be disrupted.An often misunderstood point is why the Schema Theorem is an inequality rather than an equality. The answer is in fact simple: the Theorem neglects the small, yet non-zero, probability that a string belonging to the schema  will be created "from scratch" by mutation of a single string (or recombination of two strings) that did not belong to  in the previous generation.