69,976 research outputs found
Directed Containers as Categories
Directed containers make explicit the additional structure of those
containers whose set functor interpretation carries a comonad structure. The
data and laws of a directed container resemble those of a monoid, while the
data and laws of a directed container morphism those of a monoid morphism in
the reverse direction. With some reorganization, a directed container is the
same as a small category, but a directed container morphism is opcleavage-like.
We draw some conclusions for comonads from this observation, considering in
particular basic constructions and concepts like the opposite category and a
groupoid.Comment: In Proceedings MSFP 2016, arXiv:1604.0038
When is a container a comonad?
Abbott, Altenkirch, Ghani and others have taught us that many parameterized
datatypes (set functors) can be usefully analyzed via container representations
in terms of a set of shapes and a set of positions in each shape. This paper
builds on the observation that datatypes often carry additional structure that
containers alone do not account for. We introduce directed containers to
capture the common situation where every position in a data-structure
determines another data-structure, informally, the sub-data-structure rooted by
that position. Some natural examples are non-empty lists and node-labelled
trees, and data-structures with a designated position (zippers). While
containers denote set functors via a fully-faithful functor, directed
containers interpret fully-faithfully into comonads. But more is true: every
comonad whose underlying functor is a container is represented by a directed
container. In fact, directed containers are the same as containers that are
comonads. We also describe some constructions of directed containers. We have
formalized our development in the dependently typed programming language Agda
Three-year-olds' understanding of the consequences of joint commitments
No external funding has supported the current work.Here we investigate the extent of children's understanding of the joint commitments inherent in joint activities. Three-year-old children either made a joint commitment to assemble a puzzle with a puppet partner, or else the child and puppet each assembled their own puzzle. Afterwards, children who had made the joint commitment were more likely to stop and wait for their partner on their way to fetch something, more likely to spontaneously help their partner when needed, and more likely to take over their partner's role when necessary. There was no clear difference in children's tendency to tattle on their partner's cheating behavior or their tendency to distribute rewards equally at the end. It thus appears that by 3 years of age making a joint commitment to act together with others is beginning to engender in children a "we"-intentionality which holds across at least most of the process of the joint activity until the shared goal is achieved, and which withstands at least some of the perturbations to the joint activity children experience.Publisher PDFPeer reviewe
Why do dogs (Canis familiaris) select the empty container in an observational learning task?
Many argue that dogs show unique susceptibility to human communicative signals that make them suitable for being engaged in complex co-operation with humans. It has also been revealed that socially provided information is particularly effective in influencing the behaviour of dogs even when the human’s action demonstration conveys inefficient or mistaken solution of task. It is unclear, however, how the communicative nature of the demonstration context and the presence of the human demonstrator affect the dogs’ object-choice behaviour in observational learning situations. In order to unfold the effects of these factors, 76 adult pet dogs could observe a communicative or a non-communicative demonstration in which the human retrieved a tennis ball from under an opaque container while manipulating another distant and obviously empty (transparent) one. Subjects were then allowed to choose either in the presence of the demonstrator or after she left the room. Results showed a significant main effect of the demonstration context (presence or absence of the human’s communicative signals), and we also found some evidence for the response-modifying effect of the presence of the human demonstrator during the dogs’ choice. That is, dogs predominantly chose the baited container, but if the demonstration context was communicative and the human was present during the dogs’ choice, subjects’ tendency to select the baited container has been reduced. In agreement with the studies showing sensitivity to human’s communicative signals in dogs, these findings point to a special form of social influence in observational learning situations when it comes to learning about causally opaque and less efficient (compared to what comes natural to the dog) action demonstrations
Directed network modules
A search technique locating network modules, i.e., internally densely
connected groups of nodes in directed networks is introduced by extending the
Clique Percolation Method originally proposed for undirected networks. After
giving a suitable definition for directed modules we investigate their
percolation transition in the Erdos-Renyi graph both analytically and
numerically. We also analyse four real-world directed networks, including
Google's own webpages, an email network, a word association graph and the
transcriptional regulatory network of the yeast Saccharomyces cerevisiae. The
obtained directed modules are validated by additional information available for
the nodes. We find that directed modules of real-world graphs inherently
overlap and the investigated networks can be classified into two major groups
in terms of the overlaps between the modules. Accordingly, in the
word-association network and among Google's webpages the overlaps are likely to
contain in-hubs, whereas the modules in the email and transcriptional
regulatory networks tend to overlap via out-hubs.Comment: 21 pages, 10 figures, version 2: added two paragaph
Wind-induced drift of objects at sea: the leeway field method
A method for conducting leeway field experiments to establish the drift
properties of small objects (0.1-25 m) is described. The objective is to define
a standardized and unambiguous procedure for condensing the drift properties
down to a set of coefficients that may be incorporated into existing stochastic
trajectory forecast models for drifting objects of concern to search and rescue
operations and other activities involving vessels lost at sea such as
containers with hazardous material.
An operational definition of the slip or wind and wave-induced motion of a
drifting object relative to the ambient current is proposed. This definition
taken together with a strict adherence to 10 m wind speed allows us to refer
unambiguously to the leeway of a drifting object. We recommend that all objects
if possible be studied using what we term the direct method, where the object's
leeway is studied directly using an attached current meter.
We divide drifting objects into four categories, depending on their size. For
the smaller objects (less than 0.5 m), an indirect method of measuring the
object's motion relative to the ambient current must be used. For larger
objects, direct measurement of the motion through the near-surface water masses
is strongly recommended. Larger objects are categorized according to the
ability to attach current meters and wind monitoring systems to them.
The leeway field method proposed here is illustrated with results from field
work where three objects were studied in their distress configuration; a 1:3.3
sized model of a 40-ft Shipping container, a World War II mine and a 220 l
(55-gallon) oil drum.Comment: 33 pages, 12 figures, 3 table
Legal Aspects which Implement Good Practice Measures in the Management of Construction and Demolition Waste
The construction industry, one of the most important ones in the development of a country, generates unavoidable impacts on the environment. The social demand towards greater respect for the environment is a high and general outcry. Therefore, the construction industry needs to reduce the impact it produces. Proper waste management is not enough; we must take a further step in environmental management, where new measures need to be introduced for the prevention at source, such as good practices to promote recycling. Following the amendment of the legal frame applicable to Construction and Demolition Waste (C&D waste), important developments have been incorporated in European and International laws, aiming to promote the culture of reusing and recycling. This change of mindset, that is progressively taking place in society, is allowing for the consideration of C&D waste no longer as an unusable waste, but as a reusable material. The main objective of the work presented in this paper is to enhance C&D waste management systems through the development of preventive measures during the construction process. These measures concern all the agents intervening in the construction process as only the personal implication of all of them can ensure an efficient management of the C&D waste generated. Finally, a model based on preventive measures achieves organizational cohesion between the different stages of the construction process, as well as promoting the conservation of raw materials through the use and waste minimization. All of these in order to achieve a C&D waste management system, whose primary goal is zero waste generatio
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