Storing and Indexing Plan Derivations through Explanation-based Analysis of Retrieval Failures

Case-Based Planning (CBP) provides a way of scaling up domain-independent planning to solve large problems in complex domains. It replaces the detailed and lengthy search for a solution with the retrieval and adaptation of previous planning experiences. In general, CBP has been demonstrated to improve performance over generative (from-scratch) planning. However, the performance improvements it provides are dependent on adequate judgements as to problem similarity. In particular, although CBP may substantially reduce planning effort overall, it is subject to a mis-retrieval problem. The success of CBP depends on these retrieval errors being relatively rare. This paper describes the design and implementation of a replay framework for the case-based planner DERSNLP+EBL. DERSNLP+EBL extends current CBP methodology by incorporating explanation-based learning techniques that allow it to explain and learn from the retrieval failures it encounters. These techniques are used to refine judgements about case similarity in response to feedback when a wrong decision has been made. The same failure analysis is used in building the case library, through the addition of repairing cases. Large problems are split and stored as single goal subproblems. Multi-goal problems are stored only when these smaller cases fail to be merged into a full solution. An empirical evaluation of this approach demonstrates the advantage of learning from experienced retrieval failure.Comment: See http://www.jair.org/ for any accompanying file

The 'Nowhere' Children: Patriarchy and the Role of Girls in India's Rural Economy

The paper is motivated by an apparent paradox – boys seem to participate more both in the labour market and in school than girls. This pattern breaks down once we take the household work done by girls into account. In this paper, we find that there is symmetry between the factors that make women’s contribution to the household economy less ‘visible’ than men’s and the factors that reduce girl’s involvement in outside work. Both are related to the kind of sociocultural environment in which households operate in India. Analysing the School, Work and household chores options for girls, we find that the kinship system prevalent in different regions as well as amongst different religions and castes is a significant determinant of these choices. In addition, we find that increases in household income do not decrease the probability of girls doing household chores, reinforcing our conclusion that non-economic factors are important. Our results confirm, once again, that while daughter’s labour complements mother’s work within family enterprises, it substitutes for mothers in household chores when the mother works outside the home.Child work, Girl child, kinship systems, patriarchy, household chores, India

Planning Graph as a (Dynamic) CSP: Exploiting EBL, DDB and other CSP Search Techniques in Graphplan

This paper reviews the connections between Graphplan's planning-graph and the dynamic constraint satisfaction problem and motivates the need for adapting CSP search techniques to the Graphplan algorithm. It then describes how explanation based learning, dependency directed backtracking, dynamic variable ordering, forward checking, sticky values and random-restart search strategies can be adapted to Graphplan. Empirical results are provided to demonstrate that these augmentations improve Graphplan's performance significantly (up to 1000x speedups) on several benchmark problems. Special attention is paid to the explanation-based learning and dependency directed backtracking techniques as they are empirically found to be most useful in improving the performance of Graphplan

Planning Graph Heuristics for Belief Space Search

Some recent works in conditional planning have proposed reachability heuristics to improve planner scalability, but many lack a formal description of the properties of their distance estimates. To place previous work in context and extend work on heuristics for conditional planning, we provide a formal basis for distance estimates between belief states. We give a definition for the distance between belief states that relies on aggregating underlying state distance measures. We give several techniques to aggregate state distances and their associated properties. Many existing heuristics exhibit a subset of the properties, but in order to provide a standardized comparison we present several generalizations of planning graph heuristics that are used in a single planner. We compliment our belief state distance estimate framework by also investigating efficient planning graph data structures that incorporate BDDs to compute the most effective heuristics. We developed two planners to serve as test-beds for our investigation. The first, CAltAlt, is a conformant regression planner that uses A* search. The second, POND, is a conditional progression planner that uses AO* search. We show the relative effectiveness of our heuristic techniques within these planners. We also compare the performance of these planners with several state of the art approaches in conditional planning

Growth Response to Competitive Shocks: Market Structure Dynamics Under Liberalisation - the Case of India

Liberalisation transforms market structures through the behavioural responses of incumbent firms and entrants, large firms and small, to enhanced freedom of choice. Change in market share volatility, and change in the effective agility of small and large firms underpin changes in market structure. We analyse these processes for Indian manufacturing industries over the 18-year period from 1980, spanning the domestic liberalisation of 1985 and the more comprehensive reforms of 1991, using a data set of large and medium firms in 83 industries. We find that while market structures themselves appeared to change little, turbulence in market shares, as well as the way growth is related to size responded markedly, differing in direction and magnitude, depending on whether the liberalisation was partial and domestic, or comprehensive. We find that they tended to offset each other, leading to little visible change in market structure itself. We also find that while drivers of market structure traditionally recognised in industrial organisation studies had significant impacts on both components of concentration change, their dynamics are captured very well by a parsimonious model that has just the announcement effects - the reform dates.Liberalisation, Competitive Shocks, Firm growth, Turbulence, Market structure, India

Subcutaneous glomus tumor of chest wall

Glomus tumors are known to occur in the subungual region of fingers. Extradigital occurrences have been reported in the past but are rare. Occurrence in the anterior chest wall has not been reported. We report a case of subcutaneous glomus tumor occurring in the anterior chest wall in a 47-year-old gentleman, suffering from pain for 2 years without diagnosis, who was successfully treated by excision biopsy

AltAltp: Online Parallelization of Plans with Heuristic State Search

Despite their near dominance, heuristic state search planners still lag behind disjunctive planners in the generation of parallel plans in classical planning. The reason is that directly searching for parallel solutions in state space planners would require the planners to branch on all possible subsets of parallel actions, thus increasing the branching factor exponentially. We present a variant of our heuristic state search planner AltAlt, called AltAltp which generates parallel plans by using greedy online parallelization of partial plans. The greedy approach is significantly informed by the use of novel distance heuristics that AltAltp derives from a graphplan-style planning graph for the problem. While this approach is not guaranteed to provide optimal parallel plans, empirical results show that AltAltp is capable of generating good quality parallel plans at a fraction of the cost incurred by the disjunctive planners

Shared agency: the dominant spouse’s impact on education expenditure

In this paper, we consider whether it is the gender of the decision maker or the extent of agency that they wield that is crucial to increasing household welfare. This is an important question as development policy is often formed on the basis that placing resources in the hands of women results in greater household welfare. Indonesia provides the ideal opportunity to study this issue because it is home to ethnic groups with very different gender norms from male dominance (the patrilineal Batak) to female dominance (the matrilineal Minangkabau). Using IFLS data for three rounds, we consider the impact of decision-making by the dominant spouse on household expenditure on education. We find that, in Indonesia, when the dominant spouse (male or female) has sole control of decision-making, there is an overall negative impact on education expenditure. This leads us to argue that it is more important to consider the issue of spousal dominance, than wholly to focus on gender