Class (philosophy)

About: Class (philosophy) is a research topic. Over the lifetime, 821 publications have been published within this topic receiving 28000 citations.

Deep learning for twelve hour precipitation forecasts

Abstract: Abstract Existing weather forecasting models are based on physics and use supercomputers to evolve the atmosphere into the future. Better physics-based forecasts require improved atmospheric models, which can be difficult to discover and develop, or increasing the resolution underlying the simulation, which can be computationally prohibitive. An emerging class of weather models based on neural networks overcome these limitations by learning the required transformations from data instead of relying on hand-coded physics and by running efficiently in parallel. Here we present a neural network capable of predicting precipitation at a high resolution up to 12 h ahead. The model predicts raw precipitation targets and outperforms for up to 12 h of lead time state-of-the-art physics-based models currently operating in the Continental United States. The results represent a substantial step towards validating the new class of neural weather models.

Concept matching system

Abstract: A system for retrieving documents related to a concept from a text corpus includes a set of stored semantic classes which are combinable to express the concept each class including a set of keywords, each set of keywords including at least one keyword. Syntactic rules are applied to identified text portions which include one or more of the keywords. A rule is satisfied when keywords from the first and second semantic classes are in any one of a plurality of syntactic relationships. A concept matching module identifies text portions within the text corpus which include one or more of the keywords, for applying the syntactic rules to the text portions, and for identifying those text portions which satisfy at least one of the rules. Documents to be retrieved may include at least one of the identified text portions.

A finite axiomatization of the set of strongly valid Ockhamist formulas

Abstract: The subject of this paper is the tense and modal logic called 'Ockhamist' in [1, p. 574]. The main result is a completeness theorem for a finite axiomatization of validity relative to Ockhamist frames. This answers the question (left open in [1]) of the finite axiomatizability of this class of formulas. The Ockhamists' attitude towards tenses is an 'Actualist Indeterminist' point of view. Roughly speaking, Indeterminism pictures time as treelike; although a moment must have exactly one past it may have several possible futures. Actualism figures in the interpretation of the future tense, taking "' will happen" to mean "a holds at some moment of the 'actual' future". One consequence is that in general tensed formulas can be true or false only relative to a possible course of events, construed as the actual future. Ockhamist possibility and necessity are strictly connected with time, in that "necessary" is meant as "necessary given the past (including the present moment)": we say that c is (now) possible, whenever a is true in some possible world having the same past as the actual one. In particular, the principle of the "unpreventability of the past" holds: every proposition concerning only the past is necessarily true or necessarily false. Given a tree representing time, the actual future of a moment x is represented by a branch starting with x; it is natural to assume that the possible futures of x are represented by a set of branches satisfying suitable closure properties. Depending on how the closure properties are selected, various notions of validity can be defined: in particular, the two that in [1] are referred to as (Ockhamist) validity

Two-Way Counter Machines and Diophantine Equations

Abstract: Let Q be the class of deterministic two-way one-counter machines accepting only bounded languages. Each machine in Q has the property that in every accepting computation, the counter makes at most a fixed number of reversals. We show that the emptiness problem for Q is decidable. When the counter is unrestricted or when the machine is provided with two reversal-bounded counters, the emptiness problem becomes undecidable. The decidability of the emptiness problem for Q is useful in proving the solvability of some numbertheoretic problems. It can also be used to prove that the language L = {u1iu2i2|i≥0} cannot be accepted by any machine in Q (u1 and u2 are distinct symbols). The proof technique is new in that it does not employ the usual "pumping", "counting", or "diagonal" argument. Note that L can be accepted by a deterministic two-way machine with two counters, each of which makes exactly one reversal.

Failures in natural language systems: applications to data base query systems

Abstract: A significant class of failures in interactions with data base query systems are attributable to misconceptions or incomplete knowledge regarding the domain of discourse on the part of the user. This paper describes several types of user failures, namely, intensional failures of presumptions. These failures are distinguished from extensional failures of presumptions since they are dependent on the structure rather than the contents of the data base. A knowledge representation has been developed for the recognition of intensional failures that are due to the assumption of non-existent relationships between entities. Several other intensional failures which depend on more sophisticated knowledge representations are also discussed. Appropriate forms of corrective behavior are outlined which would enable the user to formulate queries directed to the solution of his/her particular task and compatible with the knowledge organization.