Abstract: A document retrieval system of the present invention includes an agent system that facilitates document retrieval by mediating a search request from a user to databases provided with search engines that search for a document with a keyword. When a facilitating agent is supplied with a search request containing a keyword, the facilitating agent refers to a facilitating database that stores keyword information indicating the relationship between the keyword and the databases provided with search engines for each keyword so as to determine a database agent to which the search request is to be sent out.

Abstract: If an intermediary agent device or a database agent device cannot uniquely reply to an inquiry message issued from a user agent device, it generates a conditional reply message and returns the generated message to the user agent device. When receiving the conditional reply, the user agent device presents the conditions required for the conditional reply or a reply to a user.

Abstract: A multi-dimensional Gauss distribution generating portion obtains one vector from a multi-dimensional Gauss probability distribution and outputs it as an initial momentum. An approximated energy function differential generating portion generates a gradient of an approximated energy function. A Hamilton equation integral portion integrates a Hamilton equation using a gradient of an approximated energy function for a predetermined integral period with initial conditions of an initial state and an initial momentum. The result of the integration as the state of the next alternative is output from a next alternative generating apparatus. The state is used with a high probability corresponding to the difference of approximated energy calculated by an approximated energy difference calculating portion and the difference between a value of an original energy in the present state and that in the next state.

Abstract: Regarding a reflected light from any line portion, which is parallel to the longitudinal direction of the alignment mark 11, on the alignment mark 11, the cylindrical lens 33 functions merely as a glass plate, while the cylindrical lens 34 converges the light onto a pixel on the line sensor 35a, performing optical integration and simplifying image processing. Regarding a reflected light from any line portion, which is parallel to the lateral direction of the alignment mark 11, on the alignment mark 11, the cylindrical lens 34 functions merely as a glass plate, while the cylindrical lens 33 magnifies and forms a line image on the line sensor 35a along the pixel row of that. A toroidal lens can be used in place of the cylindrical lenses 33 and 34.

Abstract: A system for aligning a mask and a semiconductor wafer comprises radiation source for producing a radiation beam, a dual focus linear Fresnel zone plate provided on the mask for focusing the radiation beam incident thereto on a surface of the semiconductor wafer which comprises a first part having a first focal length and a second part having a second focal length substantially smaller than the first focal length, a diffraction grating provided on the surface of the semiconductor wafer in correspondence to the dual focus linear Fresnel zone plate for diffracting the radiation beam focused thereon, a detector held with a predetermined relationship with respect to the radiation source and the mask for detecting the diffracted beam, a movable stage for supporting the semiconductor wafer, and a controller for moving the stage means responsive to an output signal of the detection means.

Abstract: A two-dimensional position detecting method detects a two-dimensional position of an object which has a diffraction grating provided thereon, and this diffraction grating comprises a first grating portion which extends in a first direction and a second grating portion which extends in a second direction which is perpendicular to the first direction.