Resource Bounded Unprovability of Computational Lower Bounds

This paper introduces new notions of asymptotic proofs, PT(polynomial-time)-extensions, PTM(polynomial-time Turing machine)-omega-consistency, etc. on formal theories of arithmetic including PA (Peano Arithmetic). This paper shows that P not= NP (more generally, any super-polynomial-time lower bound in PSPACE) is unprovable in a PTM-omega-consistent theory T, where T is a consistent PT-extension of PA. This result gives a unified view to the existing two major negative results on proving P not= NP, Natural Proofs and relativizable proofs, through the two manners of characterization of PTM-omega-consistency. We also show that the PTM-omega-consistency of T cannot be proven in any PTM-omega-consistent theory S, where S is a consistent PT-extension of T.Comment: 78 page

A JOINT TEST OF PRICING-TO-MARKET, MENU COST AND CURRENCY INVOICING

This paper investigates PTM behaviour and currency invoicing decisions of Canadian pork exporters in the presence of menu costs. It is shown that when export prices are negotiated in the exporter's currency, menu costs cause threshold effects in the sense that there are bounds within (outside of) which PTM is not (is) observed. Conversely, PTM is not interrupted by menu costs when export prices are denominated in the importer's currency. The empirical model focuses on pork meat exports from Canada to the U.S. and Japan. Hansen's (2000) threshold estimation procedure is used to jointly test for currency invoicing and PTM in the presence of menu costs. Inference is conducted using bootstrap methods. PTM effects are smaller when accounting for currency invoicing decisions and menu costs than under standard linear models. The data does not reject the null hypothesis that Quebec pork exporters exercise PTM behaviour in the Japanese market and invoice their sales in Japanese currency. Evidence of PTM behaviour and foreign currency invoicing is weak for the U.S. market. Ontario pork exporters do not exercise PTM behaviour in any market.International Relations/Trade,

FINDINGS OF PRICING-TO-MARKET: MARKET SEGMENTATION OR PRODUCT DIFFERENTIATION?

Pricing to market (PTM) has been examined extensively in the recent trade literature using Knetter's (1989) model. The technique is typically applied using export unit values that aggregate differentiated products. We examine the potential bias in PTM results when using export unit values using a vertical differentiation model. We find that: i) false evidence of PTM ("pseudo PTM") is always found due to aggregation when calculating export unit values, whether the law of one price (LOP) holds or not; ii)when markets are segmented, the fraction of pseudo PTM increases with the level of product differentiation. Correspondingly, our simulation results suggest that: i) it is possible to get a statistically significant estimate of the exchange rate coefficient, even when there is no real PTM; ii) the significance of the estimate increases with product differentiation.Marketing,

Import prices and pricing-to-market effects in the euro area

Pricing-to-market (PTM) behaviour implies that exporters adjust their prices to the prevailing prices in their export markets. For the importing country, PTM effects can be interpreted as a measure of the stability of domestic prices against foreign price and exchange rate developments. PTM behaviour can be attributed to the level of competitiveness and price stickiness in the importing country. This paper investigates PTM behaviour in the euro area from the importing country's perspective, for both individual countries and the euro area as a whole. Analysis firstly involves the estimation of PTM effects in the five largest euro area countries. Secondly, PTM effects in the euro area as a whole are estimated to be slightly higher than one half. The results from illustrative simulations suggest that the increase in euro-area inflation during the first two years of monetary union can be largely attributed to oil price and exchange rate developments. JEL Classification: C32, E31, F14, F47euro area, exchange-rate pass-through, import prices, pricing-to-market

Who Prices Locally? Survey Evidence of Swiss Exporters

Survey information on Swiss exporters is used to test the hypothesis that firm-specific factors, in particular firm size, are important determinants of pricing-to-market (PTM). The survey asked exporters whether they set dif- ferent prices across markets and, if so, whether price segmentation occurred because of pricing conditions in the local market or other factors. The empirical analysis is based on a probit model that regresses a binary-choice variable of PTM on firm size and other control variables. The main empirical finding is that firm size and PTM are positively and significantly correlated. A further result is that while firms whose main export market is in the Euro area are less likely to engage in PTM, firm size plays a bigger role for them. These results are robust across different PTM classifications, regression specifications, export destinations, and industrial sectors.Pricing to markets, local currency pricing, .rm size

Who Prices Locally? Survey Evidence of Swiss Exporters

Survey information on Swiss exporters is used to test the hypothesis that firm-specific factors, in particular firm size, are important determinants of pricing--to-market (PTM). The survey asked exporters whether they set different prices across markets and, if so, whether price segmentation occurred because of pricing conditions in the local market or other factors. The empirical analysis is based on a probit model that regresses a binary-choice variable of PTM on firm size and other control variables. The main empirical finding is that firm size and PTM are positively and significantly correlated. A further result is that while firms whose main export market is in the Euro area are less likely to engage in PTM, firm size plays a bigger role for them. These results are robust across different PTM classifications, regression specifications, export destinations, and industrial sectors.Pricing to markets, local currency pricing, firm size

Pricing in International Markets: a 'Small-Country' Benchmark

This study examines export pricing to market (PTM) in a ‘small-country’ context using a panel of disaggregated exports from Hong Kong since 1992. Conventional wisdom is that PTM is commonplace – except for U.S. exports. This study provides a benchmark by which to interpret the puzzling behavior of U.S. export prices. Empirically, Hong Kong’s export price behavior is comparable to that from the U.S. This similarity reinforces the idea that PTM behavior is also a function of home market conditions and the ability to price discriminate across markets. There is little evidence of differences in PTM across Hong Kong’s export destinations.pricing to market, small-country

Comparison of the performance of two reverse osmosis membranes for the final purification of olive mill wastewater

Two quite different reverse osmosis (RO) polymeric membranes were examined for the final purification of olive mill wastewater from two-phase olive mills (OMW2): the first one is a thin-film composite (TFC) membrane consisting of polyamide active layer on polysulfone ultrafiltration support, whereas the other one is a low-pressure membrane made of asymmetric polyamide. A net operating pressure (PTM) of 25 bar was found as the target for the TFC membrane, whereas for the asymmetric one a PTM of 8 bar was chosen, given that similar flux decay but still significant productivity was observed by increasing the PTM for this membrane. These results are confirmed by the fouling index (b) values calculated for each membrane. Complete removal of suspended solids, phenolic compounds and iron was achieved by both membranes. Otherwise, the asymmetric membrane ensured slightly higher organic matter (COD) and electroconductivity (EC) reduction, leading to a COD concentration in the permeate stream equal to 3.7 mg L-1 and 1.4 mg L-1 (TFC vs. asymmetric), whereas the EC values were 97.0 and 31.0 μs cm-1, respectively. This would permit reusing the purified effluent provided by both membranes in the production process and close the loop at industrial scale. Moreover, the asymmetric membrane provides a steady-state flux value of the same order of that yielded by the TFC membrane upon more than three times less PTM (14.9 L h-1m-2 at PTM = 8 bar vs. 15.2 L h-1m-2 at PTM = 25 bar), implying a reduction of the specific energy consumption above 50 %, from 0.30 ? m-3 for the TFC membrane to 0.14? m-3 for the asymmetric one. Copyright © 2015, AIDIC Servizi S.r.l