DPLL-like satisfiability problem solver over the system of anf equations

Author(s):  
A.V. Tkachev ◽  
K. V. Kalgin
1991 ◽  
Vol 3 (2) ◽  
pp. 282-291 ◽  
Author(s):  
Gadi Pinkas

Connectionist networks with symmetric weights (like Hopfield networks and Boltzmann Machines) use gradient descent to find a minimum for quadratic energy functions. We show equivalence between the problem of satisfiability in propositional calculus and the problem of minimizing those energy functions. The equivalence is in the sense that for any satisfiable well-formed formula (WFF) we can find a quadratic function that describes it, such that the set of solutions that minimizes the function is equal to the set of truth assignments that satisfy the WFF. We also show that in the same sense every quadratic energy function describes some satisfiable WFF. Algorithms are given to transform any propositional WFF into an energy function that describes it and vice versa. High-order models that use sigma-pi units are shown to be equivalent to the standard quadratic models with additional hidden units. An algorithm to convert high-order networks to low-order ones is used to implement a satisfiability problem-solver on a connectionist network. The results give better understanding of the role of hidden units and of the limitations and capabilities of symmetric connectionist models. The techniques developed for the satisfiability problem may be applied to a wide range of other problems, such as associative memories, finding maximal consistent subsets, automatic deduction, and even nonmonotonic reasoning.


2021 ◽  
Author(s):  
Ying Jie Yan ◽  
Hideharu Amano ◽  
Masashi Aono ◽  
Kaori Ohkoda ◽  
Shingo Fukuda ◽  
...  

2003 ◽  
Vol 42 (03) ◽  
pp. 203-211 ◽  
Author(s):  
J. L. G. Dietz ◽  
A. Hasman ◽  
P. F. de Vries Robbé ◽  
H. J. Tange

Summary Objectives: Many shared-care projects feel the need for electronic patient-record (EPR) systems. In absence of practical experiences from paper record keeping, a theoretical model is the only reference for the design of these systems. In this article, we review existing models of individual clinical practice and integrate their useful elements. We then present a generic model of clinical practice that is applicable to both individual and collaborative clinical practice. Methods: We followed the principles of the conversation-for-action theory and the DEMO method. According to these principles, information can only be generated by a conversation between two actors. An actor is a role that can be played by one or more human subjects, so the model does not distinguish between inter-individual and intra-individual conversations. Results: Clinical practice has been divided into four actors: service provider, problem solver, coordinator, and worker. Each actor represents a level of clinical responsibility. Any information in the patient record is the result of a conversation between two of these actors. Connecting different conversations to one another can create a process view with meta-information about the rationale of clinical practice. Such process view can be implemented as an extension to the EPR. Conclusions: The model has the potential to cover all professional activities, but needs to be further validated. The model can serve as a theoretical basis for the design of EPR-systems for shared care, but a successful EPR-system needs more than just a theoretical model.


1989 ◽  
Author(s):  
Sandra P. Marshall ◽  
Kathryn E. Barthuli ◽  
Margaret A. Brewer ◽  
Frederic E. Rose
Keyword(s):  

2001 ◽  
Vol 63 (2) ◽  
Author(s):  
Federico Ricci-Tersenghi ◽  
Martin Weigt ◽  
Riccardo Zecchina

Author(s):  
Lamiaa Mohamed Bassam Hashem ◽  
Sherihan W. Y. Gareer ◽  
Aya Mohamed Bassam Hashem ◽  
Sherihan Fakhry ◽  
Yasmin Mounir Tohamey

Abstract Background Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has always been a problem solver in troublesome breast lesions. Despite its many advantages, the encountered low specificity results in unnecessary biopsies. Diffusion-weighted MRI (DW-MRI) is a well-established technique that helps in characterizing breast lesions according to their water diffusivity. So this work aimed to assess the diagnostic performance of DW-MRI in troublesome breast lesions and see if it can replace DCE-MRI study. Results In our prospective study, we included 86 patients with mammography and/or ultrasound-detected 90 probably benign or probably malignant (BIRADS 3 or 4) breast lesions. Among the studied cases, 49/90 lesions were benign, and 41/90 were malignant. Combined analysis of morphological and kinetic findings in DCE-MRI had achieved the highest sensitivity of 95.1%. DW-MRI alone was less sensitive (73.2%) yet more specific (83.7%) than DCE-MRI (77.6%). Diagnostic accuracy of DCE-MRI was higher (85.6%) as compared to DW-MRI which was (78.9%). Conclusion DCE-MRI is the cornerstone in the workup of troublesome breast lesions. DW-MRI should not be used as supplementary tool unless contrast administration is contraindicated. Combining both DCE-MRI and DW-MRI is the ultimate technique for better lesion evaluation.


1988 ◽  
Vol 19 (4) ◽  
pp. 36-43 ◽  
Author(s):  
Adel S. Elmaghraby
Keyword(s):  

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