Showing papers by "Indian Institute of Management Calcutta published in 1992"

Performance of IDA on trees and graphs

Abstract: We present the following results about IDA * and related algorithms: • We show that IDA * is not asymptotically optimal in all of the cases where it was thought to be so. In particular, there are trees satisfying all of the conditions previously thought to guarantee asymptotic optimality for IDA *, such that IDA * will expand more than O(N) nodes, where N is the number of nodes eligible for expansion by A*. • We present a new set of necessary and sufficient conditions to guarantee that IDA * expands O(N) nodes on trees. • On trees not satisfying the above conditions, there is no best-first admissible tree search algorithm that runs in S = N/Ψ(N) (where Ψ(N) ≠ O(1)) memory and always expands O(N) nodes. • There are acyclic graphs on which IDA * expands Ω(22N) nodes.

Efficiency of connected binary block designs when a single observation is unavailable

Abstract: In this paper the problem of finding the design efficiency is considered when a single observation is unavailable in a connected binary block design. The explicit expression of efficiency is found for the resulting design when the original design is a balanced incomplete block design or a group divisible, singular or semiregular or regular with λ1>0, design. The efficiency does not depend on the position of the unavailable observation. For a regular group divisible design with λ1>0, the efficiency depends on the position of the unavailable observation. The bounds, both lower and upper, on the efficiency are given in this situation. The efficiencies of designs resulting from a balanced incomplete block design and a group divisible design are in fact high when a single observation is unavailable.

Bukharin's alternative to Stalin: Industrialisation without forced collectivisation

Abstract: Was the Bukharin alternative feasible? It is first shown that with the improvement in the Soviet economy, his ideas changed considerably from the pro‐kulak stance of the mid‐1920s. Next, we focus on his concrete proposal, eschewing forced collectivisation, to overcome the crucial grain procurement crisis of 1927–29. Then follow counter‐factual exercises, drawing also on the experiences of contemporary developing and other late industrialising countries, on the prospects of Soviet industrialisation in the 1930s, within the NEP framework; the pace of development need not have slackened. Finally, the contemporary relevance of some of Bukharin's ideas is also underlined.

E-optimal minimally connected block designs under mixed effects model

Abstract: Considering a mixed effects model in a minimally connected block design set-up, we obtain designs which areE-optimal, uniformly in the ratio of the variance components, for inference on varietal contrasts which constitute the fixed effects in the model.

Some optimal sampling designs in the presence of polynomial trends

Abstract: We consider the problem of optimal estimation of a finite population mean in the presence of polynomial trends and suggest different methods of construction of associated optimal sampling designs for various specific combinations of values of the population size N and the sample size n. Particularly for the case of quadratic trend, we give a complete listing of all such existent designs for N< 18 and also give necessary and sufficient conditions for the existence of such optimal sampling designs when N = nk, k = 2,3,4,6.