This paper presents a new method for estimating lattice parameters of a system with additive white noise. A new lattice structure filter is used to reduce the effect of additive white noise, and then, an overfitting lattice filter is proposed to obtain the ARMA parameters by using the estimated lattice parameters with additive white noise.

In order to realize flexible interaction control between user and information processing system, a special purpose user model is proposed on the basis of the knowledge-based design method of user interface system. The user-specific control knowledge of user-oriented interface environment is represented explicitly in the user model and utilized in the user-oriented interface system. Furthermore, the framework of user-oriented interface environment based on this user model called user-model-driven interface system, is proposed as one of user-adaptive human interface systems, in this paper. According to the proposed framework, a prototype system of the user-model-driven interface system is implemented and the facility of user-specific interaction control based on the user model has been verified with respect to an electronic mail handling task.

Suppose that there are terminals on two concentric circles, Cin and Cout, with Cin inside of Cout. We are given a set of nets each of which consists of a terminal on Cin and a terminal on Cout. The routing area is the annular region between the two circles. In this paper, we present an O(nk-1) time algorithm for testing whether the given net set is k-layer routable without vias, where k2 and n is the number of nets.

An optimum placement of capacitors in the layout of Switched Capacitor networks is presented in this paper. The performance of integrated circuits is generally degraded by perturbations of physical parameters of each device and parasitic strays. The optimality imposed in this paper is the minimum degradation of a transfer function with respect to the distribution of capacitance values. A capacitance value per unit area fabricated on a LSI chip is assumed to be perturbed linearly with its x and y coordinates. The capacitor placement is determined so that the effects of such perturbation of capacitances to the overall transfer-characteristics are canceled. As the result, input-output transfer function will stay nominal under the linear perturbation model with arbitrary gradients.

This paper proposes a knowledge-based design method of a protocol of a communication network system based on the knowledge-based design methodology for computer communication systems. In the proposed method, two knowledge models, i.e., the communication network architecture model (CNAM) and the communication protocol architecture model (CPAM), are introduced and a protocol design task is modeled as a successive transformation process of these knowledge models. Giving CNAM which represents the users' requirements concerning a communication network system, the requirements specification of a protocol is derived from CNAM and represented as CPAM. Then, the detailed requirements specification of a protocol is also derived from CPAM and represented by the formal description technique (FDT-Expressions). The derivations of CPAM and FDT-Expressions are executed by the transformation rules which represent the mappings between knowledge models. Due to formally defined knowledge models and mappings, the proposed method provides a framework of a systematic support of knowledge-based protocol design. In this paper, the formal definitions of CNAM and CPAM are given, then the derivation process of FDT-Expressions of a protocol is also formalized based on these knowledge models. Furthermore, a design example is demonstrated by using LOTOS as one of the FDT-Expressions of a protocol.

This paper proposes a new construction of the minimum knowledge undeniable signature scheme which solves a problem inherent in Chaum's scheme. We formulate a new proof system, the minimum knowledge interactive bi-proof system, and a pair of languages, the common witness problem, based on the random self-reducible problem. We show that any common witness problem has the minimum knowledge interactive bi-proof system. A practical construction for undeniable signature schemes is proposed based on such a proof system. These schemes provide signature confirmation and disavowal with the same protocol (or at the same time).

Circuit complexity of a Boolean function is defined to be the minimum number of gates in circuits computing the function. In general, the circuit complexity is established by deriving two types of bounds on the complexity. On one hand, an upper bound is derived by showing a circuit, of the size given by the bound, to compute a function. On the other hand, a lower bound is established by proving that a function can not be computed by any circuit of the size. There has been much success in obtaining good upper bounds, while in spite of much efforts few progress has been made toward establishing strong lower bounds. In this paper, after surveying general results concerning circuit complexity for Boolean functions, we explain recent results about lower bounds, focusing on the method of approximation.