This paper proposes an integer linear programming (ILP)-based power minimization method by partitioning into regions, first, with three different V-DD's(PM3V), and, secondly, with two different V-DD's(PM2V). T...
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This paper proposes an integer linear programming (ILP)-based power minimization method by partitioning into regions, first, with three different V-DD's(PM3V), and, secondly, with two different V-DD's(PM2V). To reduce the solving time of triple-V-DD case (PM3V), we also proposed a partitioned ILP method(p-PM3V). The proposed method provides 29% power saving on the average in the case of triple-V-DD compared to the case of single V-DD. Power reduction of PM3V compared to Clustered Voltage Scaling (CVS) was about 18%. Compared to the un-partitioned ILP formulation(PM3V), the partitioned ILP method(p-PM3V) reduced the total solution time by 46% at the cost of additional power consumption within 1.3%.
State-of-the-art SAT solvers are nowadays able to handle huge real-world instances. The key to this success is the Conflict-Driven Clause-Learning (CDCL) scheme, which encompasses a number of techniques that exploit t...
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State-of-the-art SAT solvers are nowadays able to handle huge real-world instances. The key to this success is the Conflict-Driven Clause-Learning (CDCL) scheme, which encompasses a number of techniques that exploit the conflicts that are encountered during the search for a solution. In this article, we extend these techniques to integer linear programming (ILP), where variables may take general integer values instead of purely binary ones, constraints are more expressive than just propositional clauses, and there may be an objective function to optimize. We explain how these methods can be implemented efficiently and discuss possible improvements. Our work is backed with a basic implementation showing that, even in this far less mature stage, our techniques are already a useful complement to the state of the art in ILP.
This paper deals with a problem related to the observability of discrete event systems: the initial-state opacity. Given a set of system states (the secret), a system observation is called initial-state opaque if an a...
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This paper deals with a problem related to the observability of discrete event systems: the initial-state opacity. Given a set of system states (the secret), a system observation is called initial-state opaque if an agent (named intruder), who can partially observe the system, cannot determine whether the set of initial states consistent with an event sequence is included in the secret. Such a character can describe security problems in cyber-infrastructures, such as Internet and mobile communication networks or national defense service systems. This work presents a novel on-line methodology to verify the notion of initial-state opacity of discrete event systems that are modeled by labeled Petri nets. By working on-line, the intruder records an event and exploits integer linear programming problem for checking the initial-state opacity of the system's evolution under the given observation. A set of examples are shown to shed light on the efficiency of the presented methodology. (C) 2019 ISA. Published by Elsevier Ltd. All rights reserved.
The most complete form of academic timetabling problem is the population and course timetabling problem. In this problem, there may be multiple classes of each subject, and the decision on which students are to consti...
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The most complete form of academic timetabling problem is the population and course timetabling problem. In this problem, there may be multiple classes of each subject, and the decision on which students are to constitute each class is made in concert with the decision on the timetable for each class. In order to solve this problem, it is normally simplified or decomposed in some fashion. One simplification commonly used in practice is known as blocking: it is assumed that the classes can be partitioned into sets of classes (or blocks) that will be timetabled in parallel. This restricts clashing to occur only between classes in the same block, and essentially removes the timetabling aspect of the problem, which can be carried out, once the blocks are constituted and the classes populated. The problem of constituting the blocks and populating the classes, known as the course blocking and population problem, is nevertheless a challenging problem, and provides the focus of this paper. We demonstrate, using data provided by a local high school, that integer linear programming approaches can solve the problem in a matter of seconds. Key features include remodelling to remove symmetry caused by students with identical subject selection, and the observation that in practice, only integrality of the block composition variables needs to be enforced;the class population aspects of the model have strong integrality properties. (C) 2006 Elsevier Ltd. All rights reserved.
The integer linear programming is an NP-complete problem. In this paper, a detailed discussion is given of DNA algorithms for the DNA solution of the integer linear programming. (c) 2005 Elsevier Inc. All rights reser...
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The integer linear programming is an NP-complete problem. In this paper, a detailed discussion is given of DNA algorithms for the DNA solution of the integer linear programming. (c) 2005 Elsevier Inc. All rights reserved.
Voltage control of Taiwan Power Company is investigated using a nile-based expert system. The developed expert system, which is implemented on a personal computer, is written using the artificial intelligence language...
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Voltage control of Taiwan Power Company is investigated using a nile-based expert system. The developed expert system, which is implemented on a personal computer, is written using the artificial intelligence language PROLOG. To benefit from human experts' past experience, the heuristic rules currently followed by the operators at Taiwan Power Company are compiled and coded in the rule base of the expert system. To determine the required adjustments to the various VAR control devices, an integer linear programming (LP) routine is developed using the branch and bound method. With the developed integer LP routine, integer solutions to the control variables such as switchable inductors and capacitors and transformer tap settings can be achieved by the expert system without rounding off the results. The objective function employed in this study is to minimize the number of required adjustments, making the approach suitable for practical applications. The designed expert system has been applied to correct the abnormal voltages in Taiwan Power Company during emergency conditions. It is found from the study results that the proposed expert system is a valuable aid to system operators for voltage control.
Process mining is concerned with the analysis, understanding and improvement of business processes. Process discovery, i.e. discovering a process model based on an event log, is considered the most challenging process...
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Process mining is concerned with the analysis, understanding and improvement of business processes. Process discovery, i.e. discovering a process model based on an event log, is considered the most challenging process mining task. State-of-the-art process discovery algorithms only discover local control flow patterns and are unable to discover complex, non-local patterns. Region theory based techniques, i.e. an established class of process discovery techniques, do allow for discovering such patterns. However, applying region theory directly results in complex, overfitting models, which is less desirable. Moreover, region theory does not cope with guarantees provided by state-of-the-art process discovery algorithms, both w.r.t. structural and behavioural properties of the discovered process models. In this paper we present an ILP-based process discovery approach, based on region theory, that guarantees to discover relaxed sound workflow nets. Moreover, we devise a filtering algorithm, based on the internal working of the ILP-formulation, that is able to cope with the presence of infrequent, exceptional behaviour. We have extensively evaluated the technique using different event logs with different levels of exceptional behaviour. Our experiments show that the presented approach allows us to leverage the inherent shortcomings of existing region-based approaches. The techniques presented are implemented and readily available in the HybridILPMiner package in the open-source process mining tool-kits ProM (http://***) and RapidProM (http://***).
In many applications, the Gaussian mixture serves as an important probabilistic representation of the system state. A global optimal Gaussian mixture reduction (GMR) approach based on integer linear programming (ILP) ...
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In many applications, the Gaussian mixture serves as an important probabilistic representation of the system state. A global optimal Gaussian mixture reduction (GMR) approach based on integer linear programming (ILP) is developed in this paper. Firstly, a Gaussian base set is constructed with partial merging of components of the original mixture. Secondly, by introducing auxiliary variables reasonably, the original problem of selecting the best candidates from the given Gaussian base set is formulated as an ILP problem. Finally, a global optimal solution to GMR is obtained by solving the ILP problem. The global optimum property enables it as a basis for performance comparison with different GMR algorithms.
integer linear programming (ILP) problems are harder to solve than linearprogramming (LP) problems. It doesn't work if try to round off the results of LP problems and claim they are the optimum solution. The bran...
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integer linear programming (ILP) problems are harder to solve than linearprogramming (LP) problems. It doesn't work if try to round off the results of LP problems and claim they are the optimum solution. The branch-and-bound (B&B) is the popular method to solve ILP problems. In this paper, we propose a revised B&B, which is demonstrated to be more efficient most of time. This method is extraordinarily useful when facing ILP problems with large differences between constraints and variables. It could reduce the number of constraint and work efficiently when handling ILP problems with many constraints and less variables. Even if the ILP problems have fewer constraints but many variables, we suggest using duality concept to interchange variables with constraints. Then, the revised B&B could be used to compute results very quickly. (c) 2006 Elsevier Inc. All rights reserved.
Discovering driver pathways is an essential task to understand the pathogenesis of cancer and to design precise treatments for cancer patients. Increasing evidences have been indicating that multiple pathways often fu...
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Discovering driver pathways is an essential task to understand the pathogenesis of cancer and to design precise treatments for cancer patients. Increasing evidences have been indicating that multiple pathways often function cooperatively in carcinogenesis. In this study, we propose an approach called CDPath to discover cooperative driver pathways. CDPath first uses integer linear programming to explore driver core modules from mutation profiles by enforcing co-occurrence and functional interaction relations between modules, and by maximizing the mutual exclusivity and coverage within modules. Next, to enforce cooperation of pathways and help the follow-up exact cooperative driver pathways discovery, it performs Markov clustering on pathway-pathway interaction network to cluster pathways. After that, it identifies pathways in different modules but in the same clusters as cooperative driver pathways. We apply CDPath on two TCGA datasets: breast cancer (BRCA) and endometrial cancer (UCEC). The results show that CDPath can identify known (i.e., TP53) and potential driver genes (i.e., SPTBN2). In addition, the identified cooperative driver pathways are related with the target cancer, and they are involved with carcinogenesis and several key biological processes. CDPath can uncover more potential biological associations between pathways (over 100 percent) and more cooperative driver pathways (over 200 percent) than competitive approaches. The demo codes of CDPath are available at http://***/***?name=CDPath.
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