GIVE FORMULA Nsplit and Nadapt are two new parameters which have their usage in controlling and adjusting the split criterion and dead criterion. S is the initial population size and S^i is the current population size. It should be taken into consideration that the population size will increase by one if a bacterium undergoes reproduction and decrease by one if a bacterium faces lethat consequences. As a result, the population size may change in the searching and foraging process. At the beginning of the algorithm, as S equals to S^i, the bacterium will split and reproduce when its nutrient is greater than Nsplit and die when its nutrient is less than 0.00. The population may not go

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To avoid the population size from taking extreme values, a self -adaptive strategy is introduced: if S^i is larger than S, for each Nadapt of their differences, the split threshold value will increase by one. And if S is larger than Si, for each Nadapt of their differences, the death threshold value will decrease by one. The strategy is also according to nature. Behaviors of organisms will be affected by the environment their lived.

If the population is too much to handle, the competition between the individuals will goes up and death becomes evident. If the population is small, the individuals have an ease in survival and they undergo reproduction. By this strategy, the split threshold is enhanced when population size is large and the strictness of the death condition goes up when population is small, which controls the population size and keeps it in a relatively stable range. When the nutrient of a bacterium has a value which is less than zero, but it has not died yet, it could migrate with a probability. A random number is generated and if the number is less than migration probability Pe, it will migrate and move to a randomly produced position. Nutrient of the bacterium will be reinitialized to zero. It should also be noted that the splitting, death, and migration operators are judged in sequence, if one of them is done, the algorithm will breakout from the current cycle and will not execute the rest of