Temporal Facts Research Articles

The Unique Groundability of Temporal Facts

The A‐theory and the B‐theory advance competing claims about how time is grounded. The A‐theory says that A‐facts are more fundamental in grounding time than are B‐facts, and the B‐theory says the reverse. We argue that whichever theory is true of the actual world is also true of all possible worlds containing time. We do this by arguing that time is uniquely groundable: however time is actually grounded, it is necessarily grounded in that way. It follows that if either the A‐theory or the B‐theory is actually false, then it is necessarily false.

Capturing Telic/Atelic Temporal Data Semantics: Generalizing Conventional Conceptual Models

Time provides context for all our experiences, cognition, and coordinated collective action. Prior research in linguistics, artificial intelligence, and temporal databases suggests the need to differentiate between temporal facts with goal-related (i.e., telic) from those are intrinsically devoid of culmination (i.e., atelic). To differentiate between telic and atelic data in conceptual database design, we propose an annotation-based temporal conceptual model that generalizes the of a conventional conceptual model. Our temporal conceptual design approach involves: 1) capturing using a conventional conceptual model; 2) employing annotations to differentiate between telic and atelic data that help capture when semantics; 3) specifying temporal constraints, specifically nonsequenced semantics, in the temporal data dictionary as metadata. Our proposed approach provides a mechanism to represent telic/atelic temporal using temporal annotations. We also show how these can be formally defined using constructs of the conventional conceptual model and axioms in first-order logic. Via what we refer to as the semantics of composition, i.e., implied by the interaction of annotations, we illustrate the logical consequences of representing telic/atelic data during temporal conceptual design.

ELighthouse: Enhance Solar Power Coverage in Renewable Sensor Networks

Energy harvesting from ambient resource such as solar power improves the sustainability and continuous monitoring capability of sensor nodes. However, energy conservation and harvesting can hardly provide a complete solution due to two main reasons: the energy harvesting capabilities/opportunities are seriously affected by spatial and temporal facts regarding the location of sensor deployment, and distributed processing of sensing and communication are also uneven throughout the network which leads to unbalanced energy consumption. In this paper, we propose an energy transfer system called eLighthouse to level the energy harvesting and consumption of solar-powered WSN. An energy-hub equipment has been brought forward utilizing a controlled retroreflector to forward sunlight to the appropriate nodes which urgently require recharging. The scheduling algorithm among multiple nodes is also included in this paper which helps to maintain the maximum number of nodes in active state; the localization algorithm which enables the controlled retroreflector for pointing correctly is also a key contribution of this paper. The experimental and simulation results both demonstrated that the proposed system can maximize the utilization of the solar power charging technique effectively to prolong the network lifetime and build up a sustainable WSN.

A temporal-probabilistic database model for information extraction

Temporal annotations of facts are a key component both for building a high-accuracy knowledge base and for answering queries over the resulting temporal knowledge base with high precision and recall. In this paper, we present a temporal-probabilistic database model for cleaning uncertain temporal facts obtained from information extraction methods. Specifically, we consider a combination of temporal deduction rules, temporal consistency constraints and probabilistic inference based on the common possible-worlds semantics with data lineage, and we study the theoretical properties of this data model. We further develop a query engine which is capable of scaling to very large temporal knowledge bases, with nearly interactive query response times over millions of uncertain facts and hundreds of thousands of grounded rules. Our experiments over two real-world datasets demonstrate the increased robustness of our approach compared to related techniques based on constraint solving via Integer Linear Programming (ILP) and probabilistic inference via Markov Logic Networks (MLNs). We are also able to show that our runtime performance is more than competitive to current ILP solvers and the fastest available, probabilistic but non-temporal, database engines.

Editorial introduction to the special issue

The information available to intelligent agents is often uncertain, inconsistent and incomplete. It is then crucially important to develop logics for uncertainty to achieve different complex reasoning tasks. Uncertainty is present in many applications and may be represented using different frameworks: plausibility orderings, probability theory frameworks, argumentation systems, etc. This special issue gathers five contributions that cover different aspects of reasoning under uncertainty using non classical logics. Four of the five papers are fully revised and extended versions of contributions initially presented at the Fifth International Conference on Scalable Uncertainty Management (SUM’11) The two first papers concern extensions of logic-based programming languages to deal with uncertain information. The paper by Pere Pardo, Lluis Godo entitled “t-DeLP: an argumentation-based Temporal Defeasible Logic Programming framework” deals with handling temporal information using defeasible logic. The proposed framework, called t-DeLP, allows to extend argumentation-based defeasible logic in order to represent temporal processes. The idea is to associate temporal information to literals and to define temporal logic programs are sets of basic temporal facts and (strict or defeasible) durative rules. Concepts of argumentation systems, such as the one of undefeated arguments, are redefined in this t-DeLP framework. A procedure for determining a set of warranted literals is proposed. The paper also discusses rational properties satisfied by the t-DeLP framework. The paper by Georg Gottlob,Thomas Lukasiewicz, Maria Vanina Martinez and Gerardo I. Simari entitled “Query Answering under Probabilistic Uncertainty in Datalog+/ Ontologies” concerns an extension of Datalog+/− to deal with uncertainty. The authors use Markov Logic Networks to provide a probabilistic semantics for the probabilistic Datalog+/−. They provide scalable and sound algorithms for

T-DeLP: an argumentation-based Temporal Defeasible Logic Programming framework

The aim of this paper is to propose an argumentation-based defeasible logic, called t-DeLP, that focuses on forward temporal reasoning for causal inference. We extend the language of the DeLP logical framework by associating temporal parameters to literals. A temporal logic program is a set of basic temporal facts and (strict or defeasible) durative rules. Facts and rules combine into durative arguments representing temporal processes. As usual, a dialectical procedure determines which arguments are undefeated, and hence which literals are warranted, or defeasibly follow from the program. t-DeLP, though, slightly differs from DeLP in order to accommodate temporal aspects, like the persistence of facts. The output of a t-DeLP program is a set of warranted literals, which is first shown to be non-contradictory and be closed under sub-arguments. This basic framework is then modified to deal with programs whose strict rules encode mutex constraints. The resulting framework is shown to satisfy stronger logical properties like indirect consistency and closure.

A Correspondence Theory of Exemplification

What is exemplification? A proposition that attributes a property to an object is true if the object exemplifies the property. But according to the correspondence theory, a proposition is true if the corresponding fact exists. So if the correspondence theory is correct, an exemplification of a temporal property by an object is simply the concrete circumstance of the object’s having the property. But since not all properties are temporal, not all exemplifications are circumstances, and we need to recognise timeless as well as temporal facts. This distinction allows us to solve the problem of converse relations, and to give an account of the logically complex facts which deduction allows us to know.

Querying and Manipulating Temporal Databases

Many works have focused, for over twenty five years, on the integration of the time dimension in databases (DB). However, the standard SQL3 does not yet allow easy definition, manipulation and querying of temporal DBs. In this paper, we study how we can simplify querying and manipulating temporal facts in SQL3, using a model that integrates time in a native manner. To do this, we propose new keywords and syntax to define different temporal versions for many relational operators and functions used in SQL. It then becomes possible to perform various queries and updates appropriate to temporal facts. We illustrate the use of these proposals on many examples from a real application.

Supervenience and (non-modal) reductionism in Leibniz’s philosophy of time

It has recently been suggested that, for Leibniz, temporal facts globally supervene on causal facts, with the result that worlds differing with respect to their causal facts can be indiscernible with respect to their temporal facts. Such an interpretation is at variance with more traditional readings of Leibniz’s causal theory of time, which hold that Leibniz reduces temporal facts to causal facts. In this article, I argue against the global supervenience construal of Leibniz’s philosophy of time. On the view of Leibniz defended here, he adopts a non-modal reduction of time to events, a form of reductionism that entails a strong covariation between a world’s temporal facts and its causal facts. Consequently, worlds discernible with respect to their temporal facts must be discernible with respect to their causal facts, and worlds discernible with respect to their causal facts must be discernible with respect to their temporal facts. This position strongly favors the standard identificatory reduction of time to causation often imputed to Leibniz.

II–Joseph Melia

In this paper I try to eliminate occurrents from our ontology. I argue against Simons’ position that occurrents are needed to supply truthmakers for existential claims about continuants. Nevertheless, those who would eliminate occurrents still need some account of our willingness to assert sentences that logically entail their existence. Though it turns out to be impossible to paraphrase away our reference to occurrents, I show that the truthmakers for such sentences are facts that involve only continuants. This is enough to allow us to regard our ordinary talk about occurrents as fictional. Finally, I argue that a proper conception of the underlying temporal facts about continuants can both avoid the problematic tensed theory of time and the problem of temporary intrinsics.

Back to the Present

McTaggart's famous argument that the A-series is contradictory is vitiated by an unsatisfactory conceptualization of tenses which can be corrected by making explicit their relational structure. This leads into a much sharper formulation of his apparent contradiction, and defusing this apparent contradiction requires a careful distinction between tensed and tenseless descriptions of thoughts. As a result the ‘unreality’ of tense turns out to rest on the fact that tensed descriptions of temporal facts do not capture their identity. This ‘metaphysical’ priority of tenseless over tensed descriptions of time is, however, counterbalanced by an ‘epistemological’ priority of tensed thoughts over tenseless thoughts: a conception of tense which requires a form of self-consciousness turns out to be an essential ingredient of rational thought.

The Anti-Skeptical Epistemology of the Refutation of Idealism

In the Refutation of Idealism, Kant argues first that since I am conscious of my own existence as determined in time, there must be something permanent in perception. Then he argues that the permanent can only be something outside me in space. Suppose that 'consciousness of my own existence as determined in time' means knowledge of facts about the temporal ordering of my inner states. Then in order to understand the crucial first step in the argument of the Refutation, we must ask: why does such knowledge require the existence of something permanent? Kant's answer is that all determination of time presupposes something permanent in perception (B275). Here is one interpretation of Kant's reasoning in the first step of the Refutation. Knowledge of facts about the temporal ordering of my inner states requires, obviously, the existence of such temporal facts. This follows from the truthcondition for knowing: knowledge that P requires the truth of P. By the first Analogy of Experience, the existence of any facts concerning succession in time requires the existence of a permanent in perception. So knowledge of the temporal facts about my inner states requires the existence of something permanent in perception. The foregoing interpretation of the crucial first step in the Refutation highlights the metaphysical claim that there could be no facts concerning succession unless a permanent existed. On this interpretation, the ultimate

Subjective and Objective Time

easily be introduced as a linguistic distinction between two ways of talking about time, although it is arguable that there is a corresponding distinction between two types of temporal facts. The first type of temporal language includes tense proper in the grammatical sense, temporal demonstratives such as 'now' and 'today', and the terms 'past', 'present' and 'future' which at least superficially behave as predicates of events. It is a common opinion that this is not the rag-bag which it might appear to the uninitiated. I shall follow recent practice2 in referring to the whole category as 'tensed language'. One significant feature common to this type of terminology is that any sentence involving an expression of this type has the property that not all tokens of the sentence have the same truth-value. For example a token of the sentence 'it is raining today' uttered on St Swithin's day may have the value true while one uttered on Christmas Day may have the value false. In this respect tensed language is in marked and celebrated contrast to the other type of terminology, to be called here 'untensed'. Untensed language relies on the relational predicates 'earlier than', 'later than' and 'simultaneous with', together with a liberal use of dates. By these means it is possible to produce sentences which are eternal in the sense that every one of their tokens has the same truth-value. If one token of the

Stimulus interaction and between-trials proactive interference in monkeys.

Most theoretical accounts of proactive interference in delayed-matching-to-sample paradigms focus on processes linked to time. Two experiments questioned this exclusive focus on temporal facts. Between-trials proactive interference was studied in a situation in which the similarity of consecutive trials was varied along the dimensions of color, form, and position. All of these factors as well as the similarity of sample and test contexts contributed to memory performance. A mathematical model based on the assumptions that similarity strongly influences memory-based judgements and that overall similarity is determined by the multiplicative interaction of component dimensions gave an excellent qualitative and quantitative account of the data in both experiments. These results support a broader view of factors determining proactive interference and are inconsistent with the idea that these multiple factors can be treated as independent.

The ‘Present’ in Physics

Adolf Griinbaum has put forward the view that the transitory aspect of temporal facts is wholly mind-dependent. This transitory aspect is the one in virtue of which it is usually held by commonsense that physical events do come to pass, or have a transient now-status, in an objective non-mental sense, which they lose after a while when they become wholly past. Grfinbaum mentions as examples of such events '(I) a stellar explosion that occurred several million years before time t but which is first seen on earth at time t, and (2) a lightning flash originating only a fraction of a second before t and observed at time t'. He puts his contrary view in the following way:

A Defense of McTaggart's Proof of the Unreality of Time

M o[cTAGGART'S celebrated argument to prove that time unreal runs as follows. There are two kinds of temporal fact concerning events: (a) that an event M or future; (b) that an event M before, at the same time as, or after another event N. Now facts of kind (a) cannot be reduced to facts of kind (b); and if there were no facts of kind (a), there would not genuinely be any time at all. For time essentially involves change: but change comes in only in connection with facts of kind (a). With facts of kind (b) there no change at all: if an event M precedes an event N, it always be true that M preceded N, and it always true that M would precede N. There change only in virtue of the fact that we can say of some event M, for example, that it has ceased to be and now and cease to be present and become past. But, McTaggart argues, the predicates and future involve a contradiction: for on the one hand they are incompatible predicates, and on the other to every event all three apply (or at least two of them). Someone naturally reply that the predicates which apply are not the simple and but rather, for example, will be past, is present, and was future, and that these three predicates are not incompatible. But, McTaggart claims, this move advances us no further. Instead of three, we now have nine predicates, each of which still applies to every event and some of which are incompatible, for example, the predicates was past and will be future. Admittedly the objector may again reply that the predicates which really apply to the same event are is going to have been past and was going to be future, and that these are again compatible. But McTaggart can counter this move as before, and so on indefinitely. It not at once clear where the victory lies. Every contradiction McTaggart points to the objector can dispel, but at every stage a contradiction remains. On examination, however, we see that the

The Christian Understanding of Time

The Christian understanding of time is characterised by an event which is the very centre of the Christian message, and of which it is said that it happened once and for all. This ephapax is evidently an essential part of the theology of St. Paul and of the Epistle to the Hebrews. The Christian conceives of time like everything else from this centre, i.e. from Jesus Christ, and therefore it is from this centre that our reflection upon the essence of time has to start. This must be stated explicitly because another point of departure has been suggested by traditional theology. Certainly it was an act of great intuition on the part of St. Augustine when in his Confessions he dared, for the first time in history, to put forward the idea that the world was neither timeless and eternal, nor created at a certain point in the time-series, but that the world and time were created together. Therefore if the world and time have the same beginning in creation, it becomes meaningless to ask what God did before the creation of the world. The whole schema of before and after, the framework of time, cannot be regarded as existing before creation, but as coming into being with creation, itself a temporal fact.