A focused solution to the avoidance problem

2020 ◽  
Vol 30 ◽  
Author(s):  
KARL CRARY
Keyword(s):  
Upper Bound ◽  
Type Theory ◽  
Dynamic Semantics ◽  
Prior Work ◽  
Static Semantics ◽  
The Past ◽  
Logical Foundation ◽  
Module Type ◽  
Avoidance Problem

Abstract In ML-style module type theory, sealing often leads to situations in which type variables must leave scope, and this creates a need for signatures that avoid such variables. Unfortunately, in general, there is no best signature that avoids a variable, so modules do not always enjoy principal signatures. This observation is called the avoidance problem. In the past, the problem has been circumvented using a variety of devices for moving variables so they can remain in scope. These devices work, but have heretofore lacked a logical foundation. They have also lacked a presentation in which the dynamic semantics is given on the same phrases as the static semantics, which limits their applications. We can provide a best supersignature avoiding a variable by fiat, by adding an existential signature that is the least upper bound of its instances. This idea is old, but a workable metatheory has not previously been worked out. This work resolves the metatheoretic issues using ideas borrowed from focused logic. We show that the new theory results in a type discipline very similar to the aforementioned devices used in prior work. In passing, this gives a type-theoretic justification for the generative stamps used in the early days of the static semantics of ML modules. All the proofs are formalized in Coq.

Making Memories Unavailable

2007 ◽  
Vol 215 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Karl-Heinz Bäuml
Keyword(s):  
Memory Representation ◽  
Prior Work ◽  
Experimental Paradigm ◽  
Memory Tests ◽  
Inhibitory Processes ◽  
The Past ◽  
Wide Range ◽  
Extended Range ◽  
Subsequent Recall ◽  
Retrieval Blocking

Abstract. Research from the past decades has shown that cuing and retrieval are not always beneficial for episodic memory and can also be detrimental. Prior work assumed that these detrimental effects are caused by retrieval blocking, in which cuing and retrieval strengthen material and the repeated involuntary sampling of the strengthened material hinders subsequent recall of nonstrengthened targets. Using a new experimental paradigm and an extended range of memory tests, recent research indicates that the detrimental effects of retrieval and cuing occur across a wide range of memory tests and are likely to be the result of inhibitory processes. These inhibitory processes impair the nonretrieved and noncue items' memory representation and make these items unavailable in memory. The recent results and the new theory are reviewed and discussed.

scholarly journals I Do Not Exist. Problems for Dynamic Semantics

2018 ◽  
pp. 393-414
Author(s):  
Eduardo García Ramírez
Keyword(s):  
Common Ground ◽  
Dynamic Semantics ◽  
Recent Proposal ◽  
Static Semantics ◽  
What Is Said ◽  
Existential Constructions ◽  
The Common

According to dynamic semantics, what is said by an utterance of a sentence is determined by how the common ground is affected by the acceptance of such utterance. It has been claimed that dynamic semantics offers an account of what is said by an utterance in a context that excels that of traditional static semantics. Assertions of negative existential constructions, of the form ‘X does not exist’, are a case in point. These assertions traditionally pose a problem for philosophers of language. A recent proposal, owed to Clapp (2008), argues that static semantics is unable to solve the problem and offers a dynamic semantics account that promises to succeed. In this paper I want to challenge this account and, more generally, the scope of the dynamic semantics framework. I will offer a counterexample, inspired by “answering machine” uses of indexical and demonstrative expressions, to show how dynamic semantics fails.  I conclude by considering the merits of both static and dynamic accounts.

Emerging Research and Trends

2021 ◽  
pp. 367-399
Keyword(s):  
Case Studies ◽  
Model Development ◽  
Business Partnerships ◽  
Prior Work ◽  
Scholarly Journals ◽  
The Past ◽  
Insight Into

This chapter serves as a review of the emerging research related to academy-business partnerships by examining dissertations, masters theses, and some reports in the past few decades. Given that most research from dissertations is not published in scholarly journals nor books, this review provides insight into the exploration of relevant topics. An attempt has been made to cluster prior work into related groupings so that a portrait of existing research can emerge. The sparse studies included in this review yielded thin clusters of research on model development, fiscal adaptations, and idiosyncratic case studies. The largest grouping of somewhat fragmented research is clustered around examinations of individuals within the partnerships and partnership-making; this latter grouping explores the various actors from the business or academy sides of such partnerships. A summary of a NACRO survey is also included to provide research-based perspectives of actual academy-business partnerships.

scholarly journals Chiral Separation of rac-Propylene Oxide on Penicillamine Coated Gold NPs

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1716
Author(s):  
Nisha Shukla ◽  
Zachary Blonder ◽  
Andrew J. Gellman
Keyword(s):  
Propylene Oxide ◽  
Room Temperature ◽  
Adsorption Properties ◽  
Time Dependent ◽  
Prior Work ◽  
Au Nps ◽  
The Past ◽  
Racemic Mixtures ◽  
Enantioselective Adsorption ◽  
Gold Nps

The surfaces of chemically synthesized spherical gold NPs (Au-NPs) have been modified using chiral L- or D-penicillamine (Pen) in order to impart enantioselective adsorption properties. These chiral Au-NPs have been used to demonstrate enantioselective adsorption of racemic propylene oxide (PO) from aqueous solution. In the past we have studied enantioselective adsorption of racemic PO on L- or D-cysteine (Cys)-coated Au-NPs. This prior work suggested that adsorption of PO on Cys-coated Au-NPs equilibrates within an hour. In this work, we have studied the effect of time on the enantioselective adsorption of racemic PO from solution onto chiral Pen/Au-NPs. Enantioselective adsorption of PO on chiral Pen/Au-NPs is time-dependent but reaches a steady state after ~18 h at room temperature. More importantly, L- or D-Pen/Au-NPs are shown to adsorb R- or S-PO enantiospecifically and to separate the two PO enantiomers from racemic mixtures of RS-PO.

scholarly journals Expression Compatibility Problem

10.29007/xlbn ◽  
2018 ◽  
Author(s):  
Seyed Hossein Haeri ◽  
Sibylle Schupp
Keyword(s):  
Software Engineering ◽  
Formal Model ◽  
Dynamic Semantics ◽  
Static Semantics ◽  
Component Based Software Engineering

We solve the Expression Compatibility Problem (ECP) – a variation of the famous Expression Problem (EP) which, in addition to the classical EP concerns, takes into consideration the replacement, refinement, and borrowing of algebraic datatype (ADT) cases. ECP describes ADT cases as components and promotes ideas from Lightweight Family Polymorphism, Class Sharing, and Expression Families Problem. Our solution is based on a formal model for Component-Based Software Engineering that pertains to the Expression Problem. We provide the syntax, static semantics, and dynamic semantics ofour model. We also show that our model can be used to solve the Expression FamiliesProblem as well. Moreover, we show how to embed the model in Scala.

scholarly journals Scanning along a compressed timeline of the future

2017 ◽  
Author(s):  
Inder Singh ◽  
Marc W. Howard
Keyword(s):  
Computational Models ◽  
Temporal Order ◽  
Test Phase ◽  
Search Model ◽  
Psychological Processes ◽  
Prior Work ◽  
Short Term ◽  
The Past ◽  
The Future ◽  
Temporal Order Judgments

AbstractSeveral authors have suggested a deep symmetry between the psychological processes that underlie our ability to remember the past and make predictions about the future. The judgment of recency (JOR) task measures temporal order judgments for the past by presenting pairs of probe stimuli; participants choose the probe that was presented more recently. We performed a short-term relative JOR task and introduced a novel judgment of imminence (JOI) task to study temporal order judgments for the future. In the JOI task, participants were trained on a probabilistic sequence. During a test phase, the sequence was occasionally interrupted with pairs of probes. Participants chose the probe that they expected would be presented sooner. Replicating prior work, we found that in JOR the correct RT depended only on the recency of the more recent probe. This suggests that memory for the past was supported by a backward self-terminating search model operating on a temporally-organized representation of the past. Analogously, in the JOI task we find that correct RT depended only on the imminence of the more imminent probe. By analogy to the JOR results, this suggests a forward self-terminating search model operating on a temporally-organized representation of the future. Critically, in both JOR and JOI the increase in RT with recency/imminence was sublinear, suggesting that both the timeline for the future and the timeline of the past are compressed. These results place strong constraints on computational models for constructing the predicted future.

scholarly journals Theoretical and Practical Aspects Related to the Avoidability of Patterns in Words

2019 ◽  
Author(s):  
Kamelia Reshadi
Keyword(s):  
Computer Program ◽  
Constraint Satisfaction ◽  
Major Part ◽  
Constraint Satisfaction Problems ◽  
Final Part ◽  
Combinatorics On Words ◽  
Sat Solvers ◽  
The Past ◽  
The One ◽  
Avoidance Problem

This thesis concerns repetitive structures in words. More precisely, it contributes to studying appearance and absence of such repetitions in words. In the first and major part of this thesis, we study avoidability of unary patterns with permutations. The second part of this thesis deals with modeling and solving several avoidability problems as constraint satisfaction problems, using the framework of MiniZinc. Solving avoidability problems like the one mentioned in the past paragraph required, the construction, via a computer program, of a very long word that does not contain any word that matches a given pattern. This gave us the idea of using SAT solvers. Representing the problem-based SAT solvers seemed to be a standardised, and usually very optimised approach to formulate and solve the well-known avoidability problems like avoidability of formulas with reversal and avoidability of patterns in the abelian sense too. The final part is concerned with a variation on a classical avoidance problem from combinatorics on words. Considering the concatenation of i different factors of the word w, pexp_i(w) is the supremum of powers that can be constructed by concatenation of such factors, and RTi(k) is then the infimum of pexp_i(w). Again, by checking infinite ternary words that satisfy some properties, we calculate the value RT_i(3) for even and odd values of i.

‘The past isn't dead … it's deadly’: Horror, History and Locale inWhitechapel

2014 ◽  
Vol 11 (1) ◽  
pp. 68-85 ◽  
Author(s):  
Rebecca Williams
Keyword(s):  
Prior Work ◽  
Partial Knowledge ◽  
Television Drama ◽  
Crime Drama ◽  
Television Programming ◽  
The Past ◽  
Convincing Case

This article analyses the ITV crime drama Whitechapel (2009 –), contributing to academic understandings of the horror and Gothic genres on television. It does so by examining the importance of place in TV horror, expanding on prior work that has concentrated on the rural by focusing on television horror within the urban London district of Whitechapel which has a specific history and legacy. Given the recent boom in history television programming and the ‘potential and variety of the popular history drama in engaging with the past’ (de Groot 2009: 207), it also contributes to work on televising the past by examining how history is ambiguously represented in the Gothic crime drama. The piece explores how the past can be used to create television horror, depicting events from history as potentially threatening and as a source of dread and unease which is indebted to the Gothic's emphasis upon the past. In portraying a more nuanced relationship between the present and past, the potential limits of partial knowledge and an over-reliance on historical precedent, Whitechapel offers an instructive convincing case study regarding the intersections of place, history and Gothic/horror tropes in contemporary television drama.

scholarly journals Competitive Benchmarking: Lessons Learned from the Trading Agent Competition

AI Magazine ◽  
2012 ◽  
Vol 33 (2) ◽  
pp. 103 ◽  
Author(s):  
Wolfgang Ketter ◽  
Andreas Symeonidis
Keyword(s):  
Artificial Intelligence ◽  
Market Economy ◽  
Global Market ◽  
Lessons Learned ◽  
Prior Work ◽  
The Past ◽  
Trading Agent ◽  
Made In

Over the years, competitions have been important catalysts for progress in artificial intelligence. We describe the goal of the overall Trading Agent Competition and highlight particular competitions. We discuss its significance in the context of today’s global market economy as well as AI research, the ways in which it breaks away from limiting assumptions made in prior work, and some of the advances it has engendered over the past ten years. Since its introduction in 2000, TAC has attracted more than 350 entries and brought together researchers from AI and beyond.

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