A Note on Bisimulation and Modal Equivalence in Provability Logic and Interpretability Logic

Provability logic is a modal logic for studying properties of provability predicates, and Interpretability logic for studying interpretability between logical theories. Their natural models are GL-models and Veltman models, for which the accessibility relation is well-founded. That’s why the usual counterexample showing the necessity of finite image property in Hennessy-Milner theorem (see [1]) doesn’t exist for them. However, we show that the analogous condition must still hold, by constructing two GL-models with worlds in them that are modally equivalent but not bisimilar, and showing how these GL-models can be converted to Veltman models with the same properties. In the process we develop some useful constructions: games on Veltman models, chains, and general method of transformation from GL-models/frames to Veltman ones.     

The Self-Knowledge Gambit

If we hold that perceiving is sufficient for knowing, we can raise a powerful objection to dreaming skepticism: Skeptics assume the implausible KK-principle, because they hold that if we don’t know whether we are dreaming or perceiving p, we don’t know whether p. The rejection of the KK-principle thus suggests an anti-skeptical strategy: We can sacrifice some of our self-knowledge—our second-order knowledge—and thereby save our knowledge of the external world. I call this strategy the Self-Knowledge Gambit. I argue that the Self-Knowledge Gambit is not satisfactory, because the dreaming skeptic can avail herself of a normative counterpart to the KK-principle: When we lack second-order knowledge, we should suspend our first-order beliefs and thereby give up any first-order knowledge we might have had. The skeptical challenge is essentially a normative challenge, and one can raise it even if one rejects the KK-Principle.     

Exact solution of the one-dimensional Potts bridge model with competing interactions

Abstract

The exact solution of the q-state Potts bridge model with competing ferromagnetic and antiferromagnetic interactions is obtained and corresponding regular and critical behaviour studied.     

Factorial and Diagnostic Validity of the Beck Depression Inventory-II (BDI-II) in Croatian Primary Health Care

The aim of this study was to examine the factorial and diagnostic validity of the Beck Depression Inventory-Second Edition (BDI-II) in Croatian primary health care. Data were collected using a medical outpatient sample (N = 314). Reliability measured by internal consistency proved to be high. While the Velicer MAP Test showed that extraction of only one factor is satisfactory, confirmatory factor analysis indicated the best fit for a 3-factor structure model consisting of cognitive, affective and somatic dimensions. Receiver operating characteristics (ROC) analysis demonstrated the BDI-II to have a satisfactory diagnostic validity in differentiating between healthy and depressed individuals in this setting. The area under the curve (AUC), sensitivity and specificity were high with an optimal cut-off score of 15/16. The implications of these findings are discussed regarding the use of the BDI-II as a screening instrument in primary health care settings.     

The ground is dominant in infants’ perception of relative distance

When making relative distance judgments, adults attend to information provided by the ground surface and generally ignore information provided by ceiling surfaces. In the present study, we asked whether this ground dominance effect is present in infancy. Groups of 5- and 7-month-old infants viewed a display depicting textured ground and ceiling surfaces. Two toys, which were attached to vertical rods, were affixed to the display. The toys/rods were positioned so that one toy was specified as being nearer by the ground surface but farther away by the ceiling surface, while the other toy was specified as being farther away by the ground surface but nearer by the ceiling surface. Under monocular viewing conditions, the infants in both age groups reached preferentially for the toy that was specified as being nearer by the ground surface. This effect was significantly stronger than that observed under binocular viewing conditions. The findings indicate that the infants responded to the distance information provided by the ground surface to a greater extent than to information provided by the ceiling.     

Object and action picture naming in English and Greek

When two orthographically similar words are displayed using rapid serial visual presentation (RSVP), the repeated letters in the second critical word (W2) are not detected, leading to a deficit in reporting this word known as repetition blindness (RB). In Turkish, letters containing diacritic markings (e.g., y, ö) are considered separate letters, yet are visually highly similar to their non-diacritic analogues (s,o). Two experiments used the phenomenon of RB to investigate whether diacritic letters are represented as more similar to their non-diacritic analogues than are two unrelated letters. In Experiment 1, substantially more RB was found for words differing in just a diacritic (i y im-isim) compared to orthographic neighbours (words differing in a visually non-similar letter, such as ilim-isim). In Experiment 2, the amount of RB for identical words (isim-isim) was comparable to words that differed by a single diacritic marking (i y im-isim). We conclude that diacritic letters are mentally represented as variants of their non-diacritic analogue. Letter / word recognition researchers may be interested in pursuing these findings using standard techniques such as backward masking and orthographic priming.     

Blood flow velocity changes in anterior cerebral arteries during cognitive tasks performance

Objective

Transcranial Doppler sonography (TCD) enables monitoring of blood flow velocities (BFVs) in basal cerebral arteries during different cognitive tasks performance with great temporal resolution. So far, BFVs changes during mental activity were monitored primarily in middle cerebral arteries (MCAs) and little is known about these changes in anterior cerebral arteries (ACAs).

Aim

To determine the effect of different cognitive tasks performance on BFV changes and hemispheric dominance in ACAs and to assess the most suitable activation test for monitoring of BFV changes in ACAs.

Methods

Fourteen right-handed, healthy subjects aged 20–26 were included in the study. BFVs in both ACAs were recorded simultaneously during performance of cognitive tasks designed to activate frontal lobes: phonemic verbal fluency test (pVFT), Stroop tests and Trail Making Tests (TMTs).

Results

A statistically significant BFV increase was recorded in both ACAs during performance of all cognitive tasks. Statistically significant right ACA dominance was found during performance of pVFT and TMTB. The most significant BFV increase was obtained during performance of TMTB.

Conclusion

Our result addressed cognitive tests with great activation potential for monitoring of ACAs that might be used in distinguishing of healthy individuals and patients with neurovascular or neurodegenerative diseases.     

Infants' perception of directional alignment of texture elements on a spherical surface

By appropriately compressing texture elements on a circular surface, one can evoke the impression of being confronted with the depiction of a spherical object in the picture plane. According to Todd and Akerstrom (1987), the 3D perception of such an object can be eliminated if the optical elements are not sufficiently elongated or if they are not aligned with one another. In the current investigation, 4‐month‐old infants were tested for their ability to react to a disruption of the directional alignment variable. They were habituated to either a spherical surface or a surface the spatial layout of which was destroyed by reorienting the texture elements, and were afterwards tested with a further ellipsoid object and with a further flat surface. Data analysis revealed that the female infants, but not the male participants, preferred the novel posthabituation display, that is, the test stimulus which included a change in the orientational alignment of texture elements. These findings are discussed within the context of development of sensitivity to pictorial depth cues. It is possible that infants as young as 4 months of age respond to manipulations of the directional alignment factor per se, while older infants are capable of using this factor as a cue for 3D object shape. Copyright © 2003 John Wiley & Sons, Ltd.     

What's wrong with promising to try?

There is often something wrong with merely promising to try to φ. In this article I explain what is wrong with such promises. I argue that a promise to try to φ, when it is entirely up to us to φ, is always wrong because it hides a possible choice under the veil of our susceptibility to circumstances beyond our control. I furthermore argue that this is often also the case when matters are not entirely up to us. Finally, I contend that sometimes the promise to try places undue burdens on the promisee.