Not by equations alone

2021 ◽  
Vol 31 ◽  
Author(s):  
OLEG KISELYOV ◽  
SHIN-CHENG MU ◽  
AMR SABRY
Keyword(s):  
Good Reason ◽  
Denotational Semantics ◽  
Conventional Approach ◽  
Writing Programs ◽  
Program Model ◽  
Global State ◽  
Equational Reasoning ◽  
Technical Result ◽  
Starting Point ◽  
Individual Effects

Abstract The challenge of reasoning about programs with (multiple) effects such as mutation, jumps, or IO dates back to the inception of program semantics in the works of Strachey and Landin. Using monads to represent individual effects and the associated equational laws to reason about them proved exceptionally effective. Even then it is not always clear what laws are to be associated with a monad—for a good reason, as we show for non-determinism. Combining expressions using different effects brings challenges not just for monads, which do not compose, but also for equational reasoning: the interaction of effects may invalidate their individual laws, as well as induce emerging properties that are not apparent in the semantics of individual effects. Overall, the problems are judging the adequacy of a law; determining if or when a law continues to hold upon addition of new effects; and obtaining and easily verifying emergent laws. We present a solution relying on the framework of (algebraic, extensible) effects, which already proved itself for writing programs with multiple effects. Equipped with a fairly conventional denotational semantics, this framework turns useful, as we demonstrate, also for reasoning about and optimizing programs with multiple interacting effects. Unlike the conventional approach, equational laws are not imposed on programs/effect handlers, but induced from them: our starting point hence is a program (model), whose denotational semantics, besides being used directly, suggests and justifies equational laws and clarifies side conditions. The main technical result is the introduction of the notion of equivalence modulo handlers (“modulo observation”) or a particular combination of handlers—and proving it to be a congruence. It is hence usable for reasoning in any context, not just evaluation contexts—provided particular conditions are met. Concretely, we describe several realistic handlers for non-determinism and elucidate their laws (some of which hold in the presence of any other effect). We demonstrate appropriate equational laws of non-determinism in the presence of global state, which have been a challenge to state and prove before.

A Byzantine(?) castle in the Val di Magra: Surianum—Filattiera

1956 ◽  
Vol 24 ◽  
pp. 14-21
Author(s):  
D. A. Bullough
Keyword(s):  
Good Reason ◽  
Late Medieval ◽  
Mountain Ranges ◽  
The North ◽  
Starting Point ◽  
The Village

The steep-sloped, one-hundred-and-ninety-foot hill on the north crest of which lies the village of Filattiera dominates the valley of the Magra between Pontremoli and Aulla and provides a remarkable view of the mountain-ranges to the northeast, north and west. The village itself still has very much the appearance of a late-medieval community in which considerations of defence predominated over all others. First recorded in 1029 among lands sold to the Otbertings and subsequently an important ‘fief’ of the Malaspina, Filattiera's documented history is carried back another three centuries by a unique inscription of the reign of Aistulf (749–757) discovered in 1910 in the chapel of S. Giorgio. In spite of a puzzling reference to the destruction of idols, there seems no good reason for doubting the inscription's authenticity. It has been the starting-point of a number of local studies of great interest, coming in particular from the pen of Signor U. Formentini, which because of their publication in periodicals with a limited circulation have not attracted the attention they deserve.My own interest in Filattiera was aroused by the statement of a guide-book that the chapel of S. Giorgio was associated with the remains of a ‘castle.’

Introduction

2020 ◽  
pp. 1-6
Author(s):  
Mark Glancy
Keyword(s):  
Good Reason ◽  
Sexual Relationships ◽  
Dark Side ◽  
Archival Research ◽  
Home Movies ◽  
Starting Point ◽  
Before And After ◽  
Key Issues

Cary Grant had good reason to dislike biographies. Many of his own biographers (including those writing before and after his death) insisted that he was defined by a “dark side’ that lay hidden beneath his charm and good looks. The starting point of this book is the aim to offer a fair, sympathetic, documented account of Grant’s life, and one based on extensive archival research, including the star’s own personal papers and home movies. The Introduction also addresses what in recent times has become one of the key issues in accounts of his life, his sexuality, stating that there are few signs that he had gay relationships but many signs that he had genuinely romantic and sexual relationships with women.

scholarly journals A denotational semantics for equilibrium logic

2015 ◽  
Vol 15 (4-5) ◽  
pp. 620-634 ◽  
Author(s):  
FELICIDAD AGUADO ◽  
PEDRO CABALAR ◽  
DAVID PEARCE ◽  
GILBERTO PÉREZ ◽  
CONCEPCIÓN VIDAL
Keyword(s):  
Denotational Semantics ◽  
The Other ◽  
Compact Set ◽  
Sufficient Condition ◽  
Alternative Semantics ◽  
Equilibrium Models ◽  
Minimal Elements ◽  
Starting Point ◽  
Formal Definitions ◽  
Entailment Relations

AbstractIn this paper we provide an alternative semantics for Equilibrium Logic and its monotonic basis, the logic of Here-and-There (also known as Gödel'sG3logic) that relies on the idea ofdenotationof a formula, that is, a function that collects the set of models of that formula. Using the three-valued logicG3as a starting point and an ordering relation (for which equilibrium/stable models are minimal elements) we provide several elementary operations for sets of interpretations. By analysing structural properties of the denotation of formulas, we show some expressiveness results forG3such as, for instance, that conjunction is not expressible in terms of the other connectives. Moreover, the denotational semantics allows us to capture the set of equilibrium models of a formula with a simple and compact set expression. We also use this semantics to provide several formal definitions for entailment relations that are usual in the literature, and further introduce a new one calledstrong entailment. We say that α strongly entails β when the equilibrium models of α ∧ γ are also equilibrium models of β ∧ γ for any context γ. We also provide a characterisation of strong entailment in terms of the denotational semantics, and give an example of a sufficient condition that can be applied in some cases.

scholarly journals Automated analysis of Stateflow models

10.29007/b8gq ◽  
2018 ◽  
Author(s):  
Hamza Bourbouh ◽  
Pierre-Loic Garoche ◽  
Christophe Garion ◽  
Arie Gurfinkel ◽  
Temesghen Kahsai ◽  
...  
Keyword(s):  
Code Generation ◽  
Denotational Semantics ◽  
Automated Analysis ◽  
Cyberphysical Systems ◽  
Modeling Framework ◽  
Safety Verification ◽  
Starting Point ◽  
Compilation Process ◽  
Modal Behavior ◽  
Hierarchical State Machines

Stateflow is a widely used modeling framework for embedded and cyberphysical systems where control software interacts with physical processes. In this work, we present a framework and a fully automated safety verification technique for Stateflow models. Our approach is two-folded: (i) we faithfully compile Stateflow models into hierarchical state machines, and (ii) we use automated logic-based verification engine to decide the validity of safety properties. The starting point of our approach is a denotational semantics of Stateflow. We propose a compilation process using continuation-passing style (CPS) denotational semantics. Our compilation technique preserves the structural and modal behavior of the system. The overall approach is implemented as an open source toolbox that can be integrated into the existing Mathworks Simulink/Stateflow modeling framework. We present preliminary experimental evaluations that illustrate the effectiveness of our approach in code generation and safety verification of industrial scale Stateflow models.

scholarly journals Teacher Ethnographic Research as Epistemology: Using Ethnographic Research to Develop Reflexive Educators in Diverse Classrooms

2010 ◽  
Vol 1 (1) ◽  
pp. 27-44
Author(s):  
Porfirio M. Loeza ◽  
Margaret Roy ◽  
Arcy Devera
Keyword(s):  
Student Teachers ◽  
Ethnographic Research ◽  
Learning Needs ◽  
Global State ◽  
Cultural Complexity ◽  
Multilingual Students ◽  
Diverse Classrooms ◽  
Starting Point

Based on fieldwork, interviews and ethno-graphic research of student teachers, reflectivity is revealed as an important starting point for teachers working with diverse and multilingual students. Reflecting assist individuals as they attempt to assimilate a new cultural complexity, particularly one that is as complex as a classroom full of adolescents. Reflexive practices are essen-tial to meet the learning needs in a multilingual, multicultural and global state. Ethnographic research can indeed provide a springboard into the development of reflective and reflexive educators.

scholarly journals An Inner City Superintendent’s View on Transformational Leadership

2014 ◽  
Vol 4 (1) ◽  
pp. 26-30
Author(s):  
Ramona Bishop
Keyword(s):  
Transformational Leadership ◽  
Inner City ◽  
Student Teachers ◽  
Ethnographic Research ◽  
Learning Needs ◽  
Global State ◽  
Cultural Complexity ◽  
Multilingual Students ◽  
Starting Point

Based on fieldwork, interviews and ethno-graphic research of student teachers, reflectivity is revealed as an important starting point for teachers working with diverse and multilingual students. Reflecting assist individuals as they attempt to assimilate a new cultural complexity, particularly one that is as complex as a classroom full of adolescents. Reflexive practices are essen-tial to meet the learning needs in a multilingual, multicultural and global state. Ethnographic research can indeed provide a springboard into the development of reflective and reflexive educators.

Introduction

2020 ◽  
pp. 1-6
Author(s):  
Gerd-Rainer Horn
Keyword(s):  
World War Ii ◽  
Western Europe ◽  
Good Reason ◽  
World War ◽  
Total War ◽  
Long Period ◽  
Starting Point ◽  
European Theatre ◽  
The Moment ◽  
History Books

The moment of liberation in Western Europe forms the endpoint or the starting point of countless history books. For good reason. The final end of a murderous total war constitutes a logical marker in historians’ attempts to make sense of the past. This book takes a rather different approach. The moment of liberation is here understood as a roughly five-year-long period which formed a distinct era on both sides of 8 May 1945, the official date of the termination of hostilities in the European theatre of World War II. It includes the final months—indeed, up to two years—of war, occupation, and resistance, but also up to three years—depending on location and circumstance—of the post-liberation period....

scholarly journals Economies of Recycling, ‘Consumption Work’ and Divisions of Labour in Sweden and England

2013 ◽  
Vol 18 (1) ◽  
pp. 114-127 ◽  
Author(s):  
Kathryn Wheeler ◽  
Miriam Glucksmann
Keyword(s):  
Waste Management ◽  
Comparative Research ◽  
Global Economy ◽  
Division Of Labour ◽  
Conventional Approach ◽  
Domestic Waste ◽  
Management Processes ◽  
Starting Point ◽  
The World ◽  
Integral Role

The recycling of domestic waste has become increasingly significant over recent years with governments across the world pledging increases in their recycling rates. But success in reaching targets relies on the input and effort of the household and consumer. This article argues that the work consumers regularly perform in sorting their recyclable waste into different fractions and, in some cases, transporting this to communal sites, plays an integral role in the overall division of labour within waste management processes. We develop the concept of ‘consumption work’ drawing on comparative research in Sweden and England to show how the consumer is both at the end and starting point of a circular global economy of materials re-use. The work that consumers do has not been systematically explored as a distinctive form of labour, and we argue that treating it seriously requires revision of the conventional approach to the division of labour.

scholarly journals Halfway Between Byzantium and Serbia: Marriage Provisions of the Second Žiča Charter .

2021 ◽  
Vol 2 (1) ◽  
pp. 165-211
Author(s):  
Milica Ristić
Keyword(s):  
Canon Law ◽  
Good Reason ◽  
Customary Law ◽  
Law System ◽  
Starting Point ◽  
Huge Impact ◽  
Independent Life ◽  
Legal Transplantation ◽  
Medieval Law ◽  
Marital Law

Marking the eight hundred years anniversary of the adoption of the Žiča Charter issued by Stefan Prvovjenčani is more than a good reason to closely examine the provisions of this Charter. If we think about the historical and political context of that time, it becomes clear that the Žiča Charter provides direct information on the formative processes of the Serbian state and church. Žiča was not only the seat of the new Serbian archdiocese, but also had a central role in building the cult of the Nemanjić dynasty and especially of Stefan Prvovjenčani as its first king. The Žiča Charter, one of the oldest Serbian legal monuments, represents the determination of the first Serbian king to create a powerful Serbian state and strengthen the Serbian Orthodox Church, which would be the base of the political and legal program not only for Stefan Prvovjenčani, but also for his successors. This is reminiscent of the „symphony doctrine” that was copied from Byzantium, and in that copying, no branch of law, including marriage law, was spared. The most important part of this Charter are definitely the norms dedicated to marital law, which show that general political tendencies had a huge impact on private law too. Many legal transplants such as the prohibition of arbitrary divorce, the prohibition of kidnaping as a way of separating spouses or dowry institutions have caused radical changes in Serbian marital law; however, they were not immune to transformations under the influence of customary law and attitudes of the society of medieval Serbia. It once again proves the thesis of professor Alan Watson who claimed that legal transplants have their own, independent life in the law system that accepted them. When it comes to Serbian medieval law, that life started very early. The influence of Roman-Byzantine and canon law was already felt in the Nomokanon of Sveti Sava, and then in the Žiča Charter; in later regulations of Serbian medieval law this influence becomes quite obvious. The main topic of this paper will be the process of legal transplantation in marital law from the Byzantine Empire to Serbia and the author will also try to discover and explain certain regularities and deviations in that process. Тhe analysis of the marital provisions of the Žiča Charter is naturally imposed here as a starting point.

Apotheosis

2018 ◽  
Author(s):  
James A. Anderson
Keyword(s):  
Good Reason ◽  
Machine Intelligence ◽  
Starting Point ◽  
The Future ◽  
Entire Universe ◽  
The Universe

In the future, perhaps all styles of computation will coalesce, each compensating for the weaknesses of the others. Humans are wary of intelligence in other species for good reason, for example, Neanderthals. “The Singularity” is when all things change due to exponentially increasing machine intelligence: machines will get more intelligent and start to design themselves, causing an explosive increase in machine intelligence until, “Ultimately, the entire universe will become saturated with our intelligence. This is the destiny of the universe.” Depending on the starting point, there may be many solutions to intelligence in the Singularity, a kind of machine polytheism, but it may be that waiting without commitment and without confining, inaccurate concepts is better. A more likely future is symbiosis, where machines and humans become indispensable to each other.

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