We show that the downward-closure of a Petri net language is effectively computable. This is mainly done by using the notions defined for showing decidability of the reachability problem of Petri nets. In particular, we rely on Lambert’s construction of marked graph transition sequences — special instances of coverability graphs that allow us to extract constructively the simple regular express...

(2) Downward infrared radiation Measurements of downward infrared radiation have been conducted since the early 1990s at Tsukuba. A time-series representation of five-year running mean downward infrared radiation until 2010 shows an increasing trend at a rate of about 0.4 W/m per year (Figure 3.3-5). This is consistent with the trend seen in the results of analysis using data from all BSRN stat...

Let G be an abelian group, and F a downward directed family of subsets of G. In [6], I. Protasov and E. Zelenyuk describe the finest group topology T on G under which F converges to 0; in particular, their description yields a criterion for T to be Hausdorff. They then show that if F is the filter of cofinite subsets of a countable subset X ⊆ G (the Fréchet filter on X), there is a simpler crit...

Background and aim: Considering the widespread development of implants in dental treatment plans, linear measurements on panoramic radiography are of especial importance. In the present study we investigated the effect of head misalignment up to 15° around vertical and horizontal axes on the magnification rate of digital panoramic radiography in each part of upper and lower jaws. Materia...

Given a point set P and a class C of geometric objects, GC(P ) is a geometric graph with vertex set P such that any two vertices p and q are adjacent if and only if there is some C ∈ C containing both p and q but no other points from P . We study G5(P ) graphs where 5 is the class of downward equilateral triangles (ie. equilateral triangles with one of their sides parallel to the x-axis and the...

The problem of bottom hole effusion is an important reason for the reduction and even shutdown natural gas wells. Downward velocity string drainage recovery process, which can improve flow rate discharge more liquid from wellhead. However, depth timing a technical that has been difficult to solve by field engineers. To this problem, paper designs method select in case highly deviated wells appl...

We give an auction for downward-closed environments that generalizes the random sampling profit extraction auction for digital goods of Fiat et al. (2002). The mechanism divides the agents in to a market and a sample using a biased coin and attempts to extract the optimal revenue from the sample from the market. The latter step is done with the downward-closed profit extractor of Ha and Hartlin...