Interaction Grammars

Interaction Grammar (IG) is a grammatical formalism based on the notion of polarity. Polarities express the resource sensitivity of natural languages by modelling the distinction between saturated and unsaturated syntactic structures. Syntactic composition is represented as a chemical reaction guided by the saturation of polarities. It is expressed in a model-theoretic framework where grammars are constraint systems using the notion of tree description and parsing appears as a process of building tree description models satisfying criteria of saturation and minimality

Credibility and Monetary Policy

A highly credible monetary policy helps to reduce the degree of uncertainty that can surround the objectives of such policy. When the monetary policy pursued by the central bank is credible, the expectations of the public are focused on a target. If the public believes that the Bank will act to bring inflation back to the target, then its expectations will not react so strongly to fluctuating price trends. In turn, fluctuations in inflation, interest rates, output, and employment should be less pronounced than in the absence of such credibility. The adoption of inflation control as a monetary policy objective by some countries has led central banks to take steps to enhance the credibility of monetary policy. For the Bank of Canada, these include the publication of our Monetary Policy Report each May and November, with formal updates each February and August the initiation of communications activities across the country the use of the overnight interest rate as a short-term operating target the issuing of a press release each time the Bank changes its key rates. To date, most of the studies on this topic have concluded that success in keeping inflation within a target range has helped to increase the credibility of Canadian monetary policy. These surveys suggest that expected inflation, which stood at about 5 per cent in 1990, declined to around 2 per cent by 1999 (Chart 1, page 15). Indeed, according to these surveys, for the entire period during which the Bank has had a target range for inflation, expected inflation rates have remained within that range. Inflation expectations have also reacted very little to changes in the total CPI, suggesting that the targets have helped to focus expectations on the target rate and have thus enhanced the credibility of monetary policy (Chart 2, page 16). One particular study shows that the life of collective wage agreements in Canada has been increasing and that the number of such agreements containing cost-of-living adjustment (COLA) clauses has steadily declined. The authors of this study suggest that this may reflect the greater credibility of Canadian monetary policy (Table 1, page 16). The proportion of mortgages with five-year terms is now higher than it was in the mid-1980s, and many financial institutions have been offering 7-to 10-year mortgages. This also suggests that inflation targets have gained credibility.

A 3D biomechanical vocal tract model to study speech production control: How to take into account the gravity?

This paper presents a modeling study of the way speech motor control can deal with gravity to achieve steady-state tongue positions. It is based on simulations carried out with the 3D biomechanical tongue model developed at ICP, which is now controlled with the Lambda model (Equilibrium-Point Hypothesis). The influence of short-delay orosensory feedback on posture stability is assessed by testing different muscle force/muscle length relationships (Invariant Characteristics). Muscle activation patterns necessary to maintain the tongue in a schwa position are proposed, and the relations of head position, tongue shape and muscle activations are analyzed

Modeling the production of VCV sequences via the inversion of a biomechanical model of the tongue

A control model of the production of VCV sequences is presented, which consists in three main parts: a static forward model of the relations between motor commands and acoustic properties; the specification of targets in the perceptual space; a planning procedure based on optimization principles. Examples of simulations generated with this model illustrate how it can be used to assess theories and models of coarticulation in speech

Explosive particle production in non-commutative inflation

We consider a model of inflation which has recently been proposed in the literature and where inflation is induced by corrections to the energy density coming from the non-commutativity of spacetime. We show that the very rapid inflationary expansion typical of this model is responsible for a burst of particle production which ends inflation and leads to a radiation-dominated phase. We analytically estimate the energy density of these particles and we confront the results with more precise numerical calculations. We estimate the number of inflationary e-folds before the back-reaction of the radiation energy density overcomes the non-commutative effects and terminate inflation naturally.Comment: v2: minor typos corrected, one reference adde

The use of sensory feedback in the adaptation of perturbed /s/

The study investigates the contribution of tactile and auditory feedback in the adaptation of /s/ towards a palatal prosthesis. Five speakers were recorded via electromagnetic articulography, at first without the prosthesis, then with the prosthesis and auditory feedback masked, and finally with the prosthesis and auditory feedback available. Tongue position, jaw position and acoustic centre of gravity of productions of the sound were measured. The results show that the initial adaptation attempts without auditory feedback are dependent on the prosthesis type and directed towards reaching the original tongue palate contact pattern. Speakers with a prosthesis which retracted the alveolar ridge retracted the tongue. Speakers with a prosthesis which did not change the place of the alveolar ridge did not retract the tongue. All speakers lowered the jaw. In a second adaptation step with auditory feedback available speakers reorganised tongue and jaw movements in order to produce more subtle acoustic characteristics of the sound such as the high amplitude noise which is typical for sibilants