Hierarchies of hyper-AFLs

For a full semi-AFL K, B(K) is defined as the family of languages generated by all K-extended basic macro grammars, while H(K) B(K) is the smallest full hyper-AFL containing K; a full basic-AFL is a full AFL K such that B(K) = K (hence every full basic-AFL is a full hyper-AFL). For any full semi-AFL K, K is a full basic-AFL if and only if B(K) is substitution closed if and only if H(K) is a full basic-AFL. If K is not a full basic-AFL, then the smallest full basic-AFL containing K is the union of an infinite hierarchy of full hyper-AFLs. If K is a full principal basic-AFL (such as INDEX, the family of indexed languages), then the largest full AFL properly contained in K is a full basic-AFL. There is a full basic-AFL lying properly in between the smallest full basic-AFL and the largest full basic-AFL in INDEX

Extended macro grammars and stack controlled machines

K-extended basic macro grammars are introduced, where K is any class of languages. The class B(K) of languages generated by such grammars is investigated, together with the class LB(K) of languages generated by the corresponding linear basic grammars. For any full semi-AFL K, B(K) is a full AFL closed under iterated LB(K)-substitution, but not necessarily under substitution. For any machine type D, the stack controlled machine type corresponding to D is introduced, denoted S(D), and the checking-stack controlled machine type CS(D). The data structure of this machine is a stack which controls a pushdown of data structures from D. If D accepts K, then S(D) accepts B(K) and CS(D) accepts LB(K). Thus the classes B(K) are characterized by stack controlled machines and the classes LB(K), i.e., the full hyper-AFLs, by checking-stack controlled machines. A full basic-AFL is a full AFL K such that B(K)C K. Every full basic-AFL is a full hyper-AFL, but not vice versa. The class of OI macro languages (i.e., indexed languages, i.e., nested stack automaton languages) is a full basic-AFL, properly containing the smallest full basic-AFL. The latter is generated by the ultrabasic macro grammars and accepted by the nested stack automata with bounded depth of nesting (and properly contains the stack languages, the ETOL languages, i.e., the smallest full hyper-AFL, and the basic macro languages). The full basic-AFLs are characterized by bounded nested stack controlled machines

Tree transducers, L systems, and two-way machines

A relationship between parallel rewriting systems and two-way machines is investigated. Restrictions on the “copying power” of these devices endow them with rich structuring and give insight into the issues of determinism, parallelism, and copying. Among the parallel rewriting systems considered are the top-down tree transducer; the generalized syntax-directed translation scheme and the ETOL system, and among the two-way machines are the tree-walking automaton, the two-way finite-state transducer, and (generalizations of) the one-way checking stack automaton. The. relationship of these devices to macro grammars is also considered. An effort is made .to provide a systematic survey of a number of existing results

An Infinite Sequence of Full AFL-Structures, Each of Which Possesses an Infinite Hierarchy

We investigate different sets of operations on languages which result in corresponding algebraic structures, viz. in different types of full AFL’s (full Abstract Family of Languages). By iterating control on ETOL-systems we show that there exists an infinite sequence Cm(m⩾1) of classes of such algebraic structures (full AFL-structures): each class is a proper superset of the next class (Cm ⊃ Cm +1). In turn each class Cm contains a countably infinite hierarchy, i.e. a countably infinite chain of language families Km,n (n⩾1) such that (i) each Km,n is closed under the operations that determine C m and (ii) each K m,n is properly included in the next one: Km,n ⊂ Km,n+1

IST Austria Thesis

This dissertation concerns the automatic verification of probabilistic systems and programs with arrays by statistical and logical methods. Although statistical and logical methods are different in nature, we show that they can be successfully combined for system analysis. In the first part of the dissertation we present a new statistical algorithm for the verification of probabilistic systems with respect to unbounded properties, including linear temporal logic. Our algorithm often performs faster than the previous approaches, and at the same time requires less information about the system. In addition, our method can be generalized to unbounded quantitative properties such as mean-payoff bounds. In the second part, we introduce two techniques for comparing probabilistic systems. Probabilistic systems are typically compared using the notion of equivalence, which requires the systems to have the equal probability of all behaviors. However, this notion is often too strict, since probabilities are typically only empirically estimated, and any imprecision may break the relation between processes. On the one hand, we propose to replace the Boolean notion of equivalence by a quantitative distance of similarity. For this purpose, we introduce a statistical framework for estimating distances between Markov chains based on their simulation runs, and we investigate which distances can be approximated in our framework. On the other hand, we propose to compare systems with respect to a new qualitative logic, which expresses that behaviors occur with probability one or a positive probability. This qualitative analysis is robust with respect to modeling errors and applicable to many domains. In the last part, we present a new quantifier-free logic for integer arrays, which allows us to express counting. Counting properties are prevalent in array-manipulating programs, however they cannot be expressed in the quantified fragments of the theory of arrays. We present a decision procedure for our logic, and provide several complexity results

Immigrant Workers at Risk: The Urgent Need for Improved Workplace Safety and Health Policies and Programs

[Excerpt] Foreign-born workers are likely to toil in high-risk occupations, work in the unregulated, “informal” economy and often fear reporting workplace injuries. Many are not aware of their legal rights to safety and health on the job and to workers’ compensation if they are injured. The AFL-CIO report, Immigrant Workers at Risk: The Urgent Need for Improved Workplace Safety and Health Policies and Programs, examines how these factors contribute to the alarming rates of injury and death on the job among immigrants and discusses the detrimental economic effects of such workplace injuries and death across society

Organizations Serving Latino Communities Take Opposing Positions on Senate Bill 744

Discussion of the guest worker program in S.B. 744 passed by the U.S. Senate in 2013-14, followed by critical examination of principle positions taken by organizations and lobbyists, and key arguments used to justify their perspectives: legal protected status vs. corporations’ need for cheap, exploitable labor. Historical context provides crucial elements for discussion

Culture in the AFL Novice Classroom: Teachers\u27 Perceptions, Teaching Techniques, and Assessment.

The teaching of cultural content in the foreign language classroom has received a great deal of attention throughout the past few decades. The role of culture in the L2 classroom has been investigated and studied from different perspectives. This study investigates teachers\u27 perceptions of teaching culture in the Arabic as a foreign language novice classroom, in addition to how Arabic as foreign language teachers introduce and assess culture. The aim of this study is to explore the current teaching practices regarding cultural content in the novice classroom, in order to determine what is needed for better teaching practices that can improve the Arabic as a foreign language learner\u27s intercultural communicative competence. The data collected for this study consisted of an online questionnaire, observations of Arabic as a foreign language novice classroom, and teachers\u27 interviews. Qualitative and quantitative analysis of the findings revealed that Arabic as foreign language teachers have positive perceptions about teaching culture in the novice classroom. Although they consider teaching culture to be as important as teaching language, they use relatively few techniques for introducing culture such as culture notes, tasks and projects. For cultural resources, they rely mainly on the textbook cultural content or the spontaneous cultural content. Moreover, there are many challenges that affect teaching culture at the novice level, such as the availability of ready-made cultural content and activities, and also the time factor. In regard to assessing culture, however, while Arabic as foreign language teachers do assess the language use appropriateness, they struggle in assessing the cultural perspectives, and they have limited techniques for assessing cultural knowledge