In a search schedule determining apparatus, a target probability distribution showing a distribution of probabilities of positions of a target in a time zone is calculated based on target previous information. A search ability showing a quantitative evaluation of an ability to discover the target is calculated based on search vehicle previous information. A search effort distribution is calculated based on the target probability distribution and the search ability such that a combination of probabilities in which each of the search vehicles discovers the target has a maximum. A search schedule is automatically determined based on the target previous information and the search vehicle previous information such that the search vehicles are operated to realize the search effort distribution.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A search schedule determining apparatus comprising: a target probability distribution calculating section which calculates a target probability distribution showing a distribution of probabilities of positions where a target is predicted to exist in a predetermined time zone, based on target previous information collected previously for the target as a search object; a search ability calculating section which calculates a search ability showing a quantitative evaluation of an ability to discover the target based on search vehicle previous information collected previously for each of search vehicles; a search effort distribution calculating section which calculates a search effort distribution based on the target probability distribution and the search ability such that a combination of probabilities in which each of the search vehicles discovers the target is maximum; and a search calculating section which automatically determines a search schedule based on the target previous information and the search vehicle previous information such that the search vehicles are operated to realize the search effort distribution. 2. The search schedule determining apparatus according to claim 1, wherein the target is ships which move on ocean, and wherein each of the search vehicles is an aircraft which searches the ships while flying in air. 3. The search schedule determining apparatus according to claim 1, further comprising a search vehicle database which stores the search vehicle previous information, wherein the search vehicle previous information contains: a stand-by position where each of the search vehicles stands-by on a land before and after the search; and a search possible time showing a maximum time from when the search vehicle takes off from the stand-by position to when the search vehicle returns to the stand-by position, and wherein the search ability of the search vehicle contains distribution information of an area to be searched by the search vehicle during the search possible time and a probability. 4. The search schedule determining apparatus according to claim 3, further comprising a target database which stores the target previous information, wherein the target previous information contains: a position of the target at a predetermined reference time; a route to be selected by the target and a probability that the route is selected; and a speed of the target when the target advances on the route. 5. A search schedule determining method comprising: collecting target previous information of a target as a search object by a target distribution probability calculating section; calculating a target probability distribution showing a distribution of probabilities of positions where the target is predicted to exist in a predetermined time zone, based on the target previous information by the target distribution probability calculating section; collecting search vehicle previous information of each of search vehicles by a search ability calculating section; calculating search ability showing a quantitative evaluation of ability to discover the target based on the search vehicle previous information by a search ability calculating section; calculating a search effort distribution based on the target probability distribution and the search ability by a search effort distribution calculating section, such that a combination of the probabilities in which each of the search vehicles discovers the target is maximum; and automatically determining a search schedule based on the target previous information and the search vehicle previous information by a search schedule calculating section such that the search vehicles are operated to realize the search effort distribution. 6. A non-transitory recording medium which stores a search schedule determining program to make a computer execute the search schedule determining program to implement functions comprising: collecting target previous information of a target as a search object by a target distribution probability calculating section; calculating a target probability distribution showing a distribution of probabilities of positions where the target is predicted to exist in a predetermined time zone, based on the target previous information by the target distribution probability calculating section; collecting search vehicle previous information of each of search vehicles by a search ability calculating section; calculating search ability showing a quantitative evaluation of ability to discover the target based on the search vehicle previous information by a search ability calculating section; calculating a search effort distribution based on the target distribution probability and the search ability by a search effort distribution calculating section, such that a combination of the probabilities in which each of the search vehicles discovers the target is maximum; and automatically determining a search schedule based on the target previous information and the search vehicle previous information by a search schedule calculating section such that the search vehicles are operated to realize the search effort distribution.