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Protocol data dependencies with an application in conformance test generation
Kwast, Erik
Wijsbegeerte
conformance testing
protocol data aspects
protocols
testing
Computer and Telecommunication networks are intended to exchange and transport in-
formation in electronic form. Usually, these networks are built by connecting systems of
dierent vendors. In order to allow for the exchange of information between such systems,
communication protocols are developed and standardised by international standardisation
organisations. Communication protocols dene how communication sessions must be set
up and how information must be exchanged.
The implementations of the communication protocols, that are used in the construction of
a network, must conform to the international standards as otherwise the dierent systems
in the network will not `understand' each other. A practical method to gain condence
that an implementation conforms to the relevant communication protocol standard, is to
perform tests. This form of testing is called conformance testing.
Before the execution of conformance tests can start, it must be clear what tests must be
run. Therefore, the testing activities start with the derivation and specication of tests.
This is a time consuming and error prone activity when performed manually. Therefore,
research activities have been undertaken to develop automatic test generation methods.
As dierent communication protocol aspects can be identied, dierent tests and also
dierent test generation methods are needed.
In order to explain this, we use the following metaphor. Assume that there are two
persons that decide to play a game of chess. As they live far apart from each other, they
use the regular mail system to exchange chess moves. To colour up the game of chess, it is
decided to exchange the chess moves using coloured envelopes according to the following
rules that must be adhered to by both persons: The rst move is sent in a red envelope;
After receiving a red envelope, a white envelope must be sent; After receiving a white
envelope, a blue envelope must be sent; After receiving a blue envelope, a red envelope
must be sent. Furthermore, the chess players must adhere to the rules of the chess game.
This implies that the moves that are sent back and forth are dependent oneach other, e.g.,
a chess move can only start from an initially empty eld of the chessboard if a previous
move put a chess piece on this eld.
In order to check if the chess players play according to all the rules, two aspects must
be examined. First, it must be checked if the players use the coloured envelopes cor-
rectly, i.e., does the sequence of envelopes show a resemblance to the Dutch national ag.
Second, it must be checked if the chess moves that are exchanged constitute a correct
game of chess. The rules regarding the use of coloured envelopes and the rule that the
contents of the messages, i.e., the chess moves, must constitute a correct game of chess
can be seen as a communication protocol. For standardised communication protocols that?228
are used in networks, analogous aspects as described for the chess game, play a role in
conformance testing. The counterparts of the coloured envelopes are the dierent sorts of
communication protocol messages that can be used in a communication session. Testing
if these messages are used in the correct order is usually referred to as testing the dynamic
behaviour. The counterparts of the chess moves that are in the envelopes are the contents
of the communication protocol messages. Testing the correctness of the contents of the
messages and their mutual dependencies, is analogous to checking if the chess moves con-
stitute a correct game of chess. We refer to this as testing the communication protocol
data aspects.
A rst step towards the automatic generation of tests is to formally describe the dynamic
behaviour and data aspects. In communication protocol standards, dynamic behaviour
aspects are usually specied by means of nite state machines or similar models. A variety
of automatic test generation methods, based on nite state machines, for the derivation
of dynamic behaviour tests exist. However, for the data aspects this is dierent. These
aspects are usually described in English. So, to allow for the automatic generation of tests,
these data aspects must be specied using some sort of formal description technique.
In this thesis we investigate the aspects related to protocol data dependencies. We present
a description technique that can be used to specify dierent sorts of data dependencies.
Furthermore, we describe a method to derive conformance tests from specications that
use our description technique for the data dependencies. This method can be automated.
It can be noted that other existing test generation methods, that mainly deal with dy-
namic behaviour aspects, result in test specications in which only the ordering of the
test messages are described. The contents of the test messages are not generated and
must be added later by protocol experts. As will be clear, the contents of messages that
are used in data tests are crucial. Therefore, a data test generation method must also
generate the contents of the test messages. We have developed a method that can be used
to automatically generate the contents of test messages. This method can be used in the
derivation of data tests according to the data test generation method that is described in
this thesis. However, the test message generation method can also be used in combina-
tion with other existing test generation methods that concentrate on dynamic behaviour
aspects. This method to generate the contents of test messages is also presented in this
thesis.
1997-10-31
Dissertation
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oai:dspace.library.uu.nl:1874/872020-02-26T08:51:20Zcom_1874_296827col_1874_296828
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Art and experience
Gerwen, R.C.H.M. van
Wijsbegeerte
aestethics
philosophy of art
representation
expression
properties
experience
evaluation
definition
imagination
Kant
Baumgarten
Goodman
This three-part dissertation is on the double role of experience in art: as a subject matter, and as the vehicle for our evaluations. It argues (Part three, Chs. 7, 8) for the inclusion within contemporary analytical ‘cognitivism’ (Part one, Chs. 1-3) of certain arguments from the founding fathers of aesthetics, Baumgarten and Kant (Part two, Chs. 4-6). I argue...
1. that depiction ought to be understood in terms of anticipated resemblances (resemblance-a, for short). (Against Goodman's semi-logical deflation of resemblance, I argue that representation is not a species of denotation, nor even a species of reference, because it lacks the ability to situate its subject matter, to indexically point us to its spatio-temporal context of production.);
2. that evocation or expression hold no answer to the problem of how to conceive of the idea of a ‘representation of an experience’. ‘Intimation’, which makes use of depicted unimodal phenomenal qualities, leaving holes to be filled in by the beholder’s imagination, does. (Intimatory devices include: framing, editing, ellipsis, metaphor);
3. that a realist definition of art should distinguish four orders of artistically relevant choices. I propose that a thing or event is art if and only if it is built from phenomenally accessible material-picked on the basis of first order decisions-exhibiting second order stylistic choices made on behalf of third order, aesthetic, evaluative choices. Procedures of museums-fourth order choices-do nothing to change this--pace Dickie.
4. that-pace Sibley-an account of the nature of aesthetic properties can be derived from the discussion of John Locke’s distinction between primary and secundary qualities, as elaborated by Ian Hacking (Representing and Intervening): we can only prove a property’s existence if we have access to it through more than one modality, but what we can say about their nature depends on the stories we want to tell.
5. that aesthetic properties are secundary qualities (those which we anticipate to resemble) which play an intimating role: tertiary qualities, for short. An account of aesthetic properties should incorporate the role played in their recognition by the imagination. Because they are perceived only through our imagination, their existence remains unproven, and therefore,
6. the account of artistic evaluation should be subjectivist. It also incorporates the imagination’s constitution of the experiential dimension of the represented, hence: imaginativist subjectivism.
7. The middle-historical-part elaborates Kant’s and Baumgarten’s philosophy of art, concentrating first on the role of the sensus communis in Kant’s subjectivist conception of the judgment of taste, arguing that this conception points us towards an ideal aesthetic experience, instead of a real one;
7. Secondly, Kant’s moral analysis of art is expounded as suggested in his Critique of Judgment, sections 17 (on the ideal of beauty), 42, 49 and 59. It is argued that Kant thought that the artistic value of works of art ought to understood as analogous to how we describe a person’s expressing his inner moral nature though his facial traits and gestures.
8. Baumgarten’s philosophy of art is defended as one which stresses exactly the indexicality of person’s experiences as an analogy to how works represent experiences.
1996-10-10
Dissertation
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https://dspace.library.uu.nl/handle/1874/87
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The Correspondence between Descartes and Henricus Regius
Bos, J.J.F.M.
Wijsbegeerte
history of philosophy
history of medicine
correspondence
René Descartes
Henricus Regius
Claude Clerselier
history
philosophy
medicine
In 1638 the Dutch philosopher and physician Henricus Regius (1598 1679) introduced himself to René Descartes (1596 1650), allegedly because he owed his appointment as professor of theoretical medicine at Utrecht University to his being a Cartesian. During the following years Regius established himself as the main advocate of Cartesianism at Utrecht. In fact, he was the first university professor to teach Cartesian ideas and to publish a number of disputations, which provide a fairly complete picture of Cartesian natural philosophy.
Apart from De Vrijer s theological thesis of 1917 little has been done so far to establish the significance of Regius work or study the way in which he took up Descartes ideas and amalgamated them with his own. Although the necessary sources have become available in the past decades, there is as yet no comprehensive study on Regius and his relation to Descartes. A major obstacle to this enterprise is the defective state of the available editions of the Descartes Regius correspondence. For a clear understanding of the relation between Descartes and Regius, and for an objective and thorough assessment of Regius philosophical and medical concepts, a critical edition of the correspondence between Descartes and Regius is an essential prerequisite. It is here where the problems arise. The actual text of the letters which were exchanged between Descartes and Regius is unknown. In 1657, Claude Clerselier published 18 minutes of Descartes part of the correspondence. All that remains of Regius letters to Descartes are abstracts and quotations in Adrien Baillet s biography, published in 1691. In 1973, Esze published two unknown letters of Descartes to Regius. The order of the letters as they were published in the editions of Adam/Tannery (1964 1971: AT), Adam/Milhaud (1936 1963), Rodis-Lewis (1959) and Bordoli (1997) is based on that of Clerselier, but since the rediscovery of Regius disputations Physiologia (1641) scholars have contested the dates of various letters. However, none of the editors so far has extensively used Regius disputations as a means to arrive at a more exact date.
The aim of my research is to provide a critical reconstruction of the correspondence between Descartes and Regius. The most dramatic differences with previous editions concern Descartes part of the correspondence. I have discovered that several letters as published by Clerselier consist in fact of fragments of many more letters. Further, I have revised almost every date established by AT, either narrowing them down or giving the letters an altogether new place in the correspondence. One of the most interesting features of the present edition is that it points out the many reoccurring passages from Descartes letters in Regius Physiologia (the complete text of the first three disputations of the Physiologia is given in an appendix). As regards Regius letters to Descartes, in many cases I have been able to establish their precise date. Moreover, in clearing Baillet s at times confused way of presentation, I have arrived at an order of Regius letters and their context which sharply contrasts with the standard view. In addition, my examination of Baillet s biography has yielded several passages relevant to Regius letters which are not found in AT. Finally, the use of the many available sources, both published and unpublished, has resulted in a comprehensive historical annotation, conspicuously absent in AT, on the specific Dutch and especially Utrecht context of the relation between Regius and Descartes.
2002-03-04
Dissertation
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Metamathematics in Coq
Hendriks, Roger Dimitri Alexander
Wijsbegeerte
automated theorem proving
first-order logic
resolution
interactive theorem proving
type theory
De Bruijn indices
formalisation of logical systems
lambda-calculus
scope
adbmal-calculus
confluence
Chapter 1: Automated Proof Construction in Type Theory using Resolution.
We describe techniques to integrate resolution logic in type
theory. Refutation proofs obtained by resolution are translated
into lambda-terms, using reflection and an encoding of
resolution proofs in minimal logic. Thereby we obtain a
verification procedure for resolution proofs, and, more
importantly, we add the power of resolution theorem provers to
interactive proof construction systems based on type theory. We
introduce a novel representation of clauses in minimal logic such
that the lambda-representation of resolution steps is
linear in the size of the premisses. A clausification algorithm,
equipped with a correctness proof, is encoded in Coq.
Chapter 2: Proof Reflection in Coq.
Natural deduction for first-order logic is formalised in the
proof assistant Coq, using de Bruijn indices for variable binding.
The main judgement is of the form G |- d [:] p, stating
that d is a proof term of formula p under
hypotheses G; it can be viewed as a typing relation by the
Curry-Howard isomorphism. This relation is proved sound with
respect to Coq's native logic and is amenable to the manipulation
of formulas and of derivations. As an illustration, I define a
reduction relation on proof terms with permutative conversions and
prove the property of subject reduction.
Chapter 3: Adbmal
To make the notion of scope in the lambda-calculus
explicit, we extend the syntax of the lambda-calculus with
an end-of-scope operator adbmal. The idea is that an
adbmal x ends the scope of the matching
lambda x above it (in the term tree). Accordingly,
beta-reduction is extended to the set of scoped
lambda-terms by performing minimal scope
extrusion before performing replication as usual. We show
confluence of the resulting scoped $\beta$-reduction. Confluence of
beta-reduction for the ordinary lambda-calculus
is obtained as a corollary, by extruding scopes maximally
before forgetting them altogether. Only in this final forgetful
step, alpha-equivalence is needed. All our proofs have
been verified in Coq.
2003-10-31
Dissertation
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https://dspace.library.uu.nl/handle/1874/89
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oai:dspace.library.uu.nl:1874/902020-02-26T08:51:45Zcom_1874_296827col_1874_296828
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Ideas and Explorations : Brouwer's Road to Intuitionism
Kuiper, Johannes John Carel
Wijsbegeerte
constructive second number class
intuitionism
ur-intuition of mathematics
possible cardinalities
logic and mathematics
solipsism
continuum
objectivity
apriori
actual infinite
This dissertation is about the initial period of Brouwer's role in the foundational debate in mathematics, which took place during the first decades of the twentieth century. His intuitionistic and constructivistic attitude was a reaction to logicism (Russell, Couturat) and to Hilbert's formalism. Brouwer's own dissertation (1907) is a first introduction to his intuitionism, which was the third movement in the foundational debate. This intuitionism reached maturity from 1918 onwards, but one of my aims is to show that there are demonstrable traces of this new development of mathematics as early as 1907 and even before, viz. in his personal notes, which are composed of his numerous ideas in the field of mathematics and philosophy. To mention some important ones:
1. Mathematics is entirely independent of language. Mathematics is created by the individual mind (Brouwer certainly is a solipsist) and the role of language is limited to that of communication a mathematical content to others and is also useful for one's own memory.
2. The ur-intuition of the 'move of time', that is, the experience that two events are not coinciding, is the most fundamental basis of all mathematics. A separate space intuition (Kant) is not needed.
3. A strict constructivism. Only that what is constructed by the individual mind counts as a mathematical object.
4. Logic only describes the structure of the language of mathemqatics. Hence logic comes after mathematics, instead of being its basis.
5. An axiomatic foundation is rejected by Brouwer. Axioms only serve the purpose of describing concisely the properties of a mathematical construction.
These five items have far-reaching consequences for Brouwer's mathematical building. To mention the most relevant ones:
- The only possible cardinalities for sets are: finite, denumerably infinite, denumerably infinite unfinished and the continuum.
- The continuum is not composed of points (Aristotle already said so), but is given to us in its entirety in the ur-intuition. It can be turned into an everywhere dense measurable continuum by constructing a rational scale on it.
- Cantor's second number class does not exist as a finished totality for Brouwer, since there is no conceivable closure for the elements of this class.
- The continuum problem is a trivial one: Every well-defined subset of the continuum is finite, denumerably infinite, or has the cardinality of the continuum.
Finally, in my dissertation the sixth chapter is devoted to Brouwer's view on the application of mathematics to the human evironment and on his outlook on man and on human society in general (chapter 2 of Brouwer's dissertation). His opinion about humanity turns out to be a pessimistic one: All man's effort, when applying mathematics to the surrounding world, is aimed at a domination over his environment and over his fellow men.
2004-02-27
Dissertation
application/pdf
https://dspace.library.uu.nl/handle/1874/90
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oai:dspace.library.uu.nl:1874/16822017-07-12T13:01:36Zcom_1874_296827col_1874_296828
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The influence of large scanning eye movements on stereoscopic slant estimation of large surfaces
Ee, R. van
Erkelens, Casper J.
Biologie
The results of several experiments demonstrate that the estimated magnitude of perceived
slant of large stereoscopic surfaces increases with the duration of the presentation. In these
experiments subjects were free to make eye movements. A possible explanation for the increase is that
the visual system needs to scan the stimulus with eye movements (which take time) before it can
make a reliable estimate of slant. We investigated the influence of large scanning eye movements on
stereoscopic slant estimation of large surfaces. Six subjects estimated the magnitude of slant about the
vertical or horizontal axis induced by large-field stereograms of which one half-image was
transformed by horizontal scale, horizontal shear, vertical scale, vertical shear, divergence or rotation
relative to the other half-image. The experiment was blocked in three sessions. Each session was
devoted to one of the following fixation strategies: central fixation, peripheral (20 deg) fixation and
active scanning of the stimulus. The presentation duration in each of the sessions was 0.5, 2 or 8 sec.
Estimations were done with and without a visual reference. The magnitudes of estimated slant and
the perceptual biases were not significantly influenced by the three fixation strategies. Thus, our
results provide no support for the hypothesis that the time used for the execution of large scanning
eye movements explains the build-up of estimated slant with the duration of the stimulus
presentation.
1999-01-01
Article
application/pdf
https://dspace.library.uu.nl/handle/1874/1682
Vision Research 39, 467-479 (1999)
en
oai:dspace.library.uu.nl:1874/16832017-07-12T13:01:36Zcom_1874_296827col_1874_296828
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Perceived Visual Direction near an Occluder
Ee, R. van
Banks, Martin S.
Backus, Benjamin T.
Biologie
When an opaque object occludes a more distant object, the two eyes often see different parts of the
distant object. Hering s laws of visual direction make an interesting prediction for this situation: the
part seen by both eyes should be seen in a different direction than the part seen by one eye. We
examined whether this prediction holds by asking observers to align a vertical monocular line
segment with a nearby vertical binocular segment. We found it necessary to correct the alignment
data for vergence errors, which were measured in a control experiment, and for monocular spatial
distortions, which were also measured in a control experiment. Settings were reasonably consistent
with Hering's laws when the monocular and binocular targets were separated by 30 arcmin or more.
Observers aligned the targets as if they were viewing them from one eye only when they were
separated by 2 arcmin; this behavior is consistent with an observation reported by Erkelens and
colleagues. The same behavior was observed when the segments were horizontal and when no
visible occluder was present. Perceived visual direction when the two eyes see different parts of a
distant target is assigned in a fashion that minimizes, but does not eliminate, distortions of the shape
of the occluded object.
1999-01-01
Article
application/pdf
https://dspace.library.uu.nl/handle/1874/1683
Vision Research 39, 4085-4097 (1999)
en
oai:dspace.library.uu.nl:1874/16812017-07-12T13:01:36Zcom_1874_296827col_1874_296828
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Temporal aspects of stereoscopic slant estimation: An evaluation and extension of Howard and Kaneko's theory
Ee, R. van
Erkelens, Casper J.
Biologie
We investigated temporal aspects of stereoscopically perceived slant produced by the
following transformations: horizontal scale, horizontal shear, vertical scale, vertical shear, divergence
and rotation, between the half-images of a stereogram. Six subjects viewed large field stimuli (70 deg
diameter) both in the presence and in the absence of a visual reference. The presentation duration
was: 0.1, 0.4, 1.6, 6.4 or 25.6 s. Without reference we found the following: Rotation and divergence
evoked considerable perceived slant in a number of subjects. This finding violates the recently
published results of Howard and Kaneko. Slant evoked by vertical scale and shear was similar to
slant evoked by horizontal scale and shear but was generally less. With reference we found the
following: Vertical scale and vertical shear did not evoke slant. Slant due to rotation and divergence
was similar to slant due to horizontal scale and shear but was generally less. According to the theory
of Howard and Kaneko, perceived slant depends on the difference between horizontal and vertical
scale and shear disparities. We made their theory more explicit by translating their proposals into
linear mathematical expressions that contain weighting factors that allow for both slant evoked by
rotation or divergence, subject-dependent underestimation of slant and other related phenomena
reported in the literature. Our data for all stimulus durations and for all subjects is explained by this
unequal-weighting extension of Howard and Kaneko's theory.
1998-01-01
Article
application/pdf
https://dspace.library.uu.nl/handle/1874/1681
Vision Research 38, 3871-3882 (1998)
en
oai:dspace.library.uu.nl:1874/16782017-07-12T13:01:36Zcom_1874_296827col_1874_296828
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Stability of binocular depth perception with moving head and eyes
Ee, R. van
Erkelens, Casper J.
Biologie
We systematically analyse the binocular disparity field under various eye, head
and stimulus positions and orientations. From the literature we know that
certain classes of disparity which involve the entire disparity field (such as
those caused by horizontal lateral shift, differential rotation, horizontal scale
and horizontal shear between the entire half-images of a stereogram) lead to
relatively poor depth perception in the case of limited observation periods.
These classes of disparity are found to be similar to the classes of disparities
which are brought about by eye and head movements. Our analysis supports
the suggestion that binocular depth perception is based primarily (for the
first few hundred milliseconds) on classes of disparity that do not change as a
result of ego-movement.
1996-01-01
Article
application/pdf
https://dspace.library.uu.nl/handle/1874/1678
Vision Research 36, 3827-3842 (1996)
en
oai:dspace.library.uu.nl:1874/16792017-07-12T13:01:36Zcom_1874_296827col_1874_296828
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Anisotropy in Werner's binocular depth contrast effect
Ee, R. van
Erkelens, Casper J.
Biologie
We investigated Werner's binocular depth contrast effect. Subjects viewed stereograms consisting of a test pattern and an inducing pattern. The halfimages of the inducing pattern were either horisontally scaled or sheared relative to each other. Subjects judged the (induced) percieved slant of the test pattern. We were interested in what in uence the spatial configuratio of the test patern and the inducing pattern had on the depth contrast effect. We conclude that the depth contrast effect is a global effect. In other words it is not restricted to the location of the inducing pattern. The effect decreases with distance, however, in an anisotropic way. The depth contrast effect was presented most prominently when the test pattern was positioned in the direction along the slant (rotation) axis of the inducing pattern. We suggest that werner's depth contrast effect can be explained by the (previously reported) finding that 1) stereopsis is very sensitive to horisontal scale and shear of two stimuli relative to each other.
1996-01-01
Article
application/pdf
https://dspace.library.uu.nl/handle/1874/1679
Vision Research 36, 2253-2262 (1996)
en
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