A capability based computer system includes means, called a factory, for allowing two domains to share resources in a secure manner. Factories are special domains which, in combination with corresponding kernel functions, allow a first domain (called a builder domain) to install a program and other components in a factory for use by other domains, and then to seal the factory, thereby leaving the builder domain with no keys to the factory except a special type of entry key called a requestor key. The holders of requestor keys can use the program in the factory by invoking the requestor key. This causes the factory to set up a new special domain for the requestor which allows the requestor to use the program in the factory to process data without being able to inspect the program. Further, the factory mechanism includes means for the requestor to confirm that the factory includes no keys which could compromise the confidentiality of the requestor's data. A second aspect of the present invention is the ability to provide different memory fault resolution mechanisms (called segment keeper domains) for different memory segments.

A method is disclosed for converting operator inputs into control commands in a computer-controlled interlocking system. For standard inputs, a search method is used instead of a complicated and time-consuming syntax analysis. Using a pseudorandom technique, a search code is determined from the text entered into an input device. With the aid of this search code, the control command assigned to the input text is found in a previously compiled list of all control commands. Before being processed, the control command found is checked for agreement with the input by a direct comparison.

An image recording apparatus for making index data from a part of image information read out of a recording medium. This apparatus comprises a memory for storing information regarding a character recognition error, a searching unit for searching the image information corresponding to search data, and a changing unit for changing a part of the search data on the basis of the information stored in the memory when the image information cannot be searched by the searching unit. Preferably, the change in search data by the changing unit is stopped by a predetermined instruction or when the number of changing operations has reached a predetermined number of changing times. Or, preferably, the search data can be rewritten to the index data by a predetermined instruction. If corresponding image information doesn't exist in the input search data, a part of the search data is changed in accordance with a character recognition error ratio which has previously been obtained, so that the image information can be searched even if there is a recognition error in the index data.

A methodology for retrieving textual data objects is disclosed. The information is treated in the statistical domain by presuming that there is an underlying, latent semantic structure in the usage of words in the data objects. Estimates to this latent structure are utilized to represent and retrieve objects. A user query is recouched in the new statistical domain and then processed in the computer system to extract the underlying meaning to respond to the query.

An analogical inference apparatus for control system is disclosed in which, in order to be able to generate a control signal to a system, which is to be controlled, even when conditions to be premised are unknown, the degree of similarity between the detected control signal from a sensor incorporated in the system and one of the predetermined control conditions stored in a memory is estimated by estimation means, and then a control value is inferred in accordance with the result of the estimation.