Verified compilation of C programs with a nominal memory model

Memory models play an important role in verified compilation of imperative programming languages. A representative one is the block-based memory model of CompCert---the state-of-the-art verified C compiler. Despite its success, the abstraction over memory space provided by CompCert's memory model is still primitive and inflexible. In essence, it uses a fixed representation for identifying memory blocks in a global memory space and uses a globally shared state for distinguishing between used and unused blocks. Therefore, any reasoning about memory must work uniformly for the global memory; it is impossible to individually reason about different sub-regions of memory (i.e., the stack and global definitions). This not only incurs unnecessary complexity in compiler verification, but also poses significant difficulty for supporting verified compilation of open or concurrent programs which need to work with contextual memory, as manifested in many previous extensions of CompCert. To remove the above limitations, we propose an enhancement to the block-based memory model based on nominal techniques; we call it the nominal memory model. By adopting the key concepts of nominal techniques such as atomic names and supports to model the memory space, we are able to 1) generalize the representation of memory blocks to any types satisfying the properties of atomic names and 2) remove the global constraints for managing memory blocks, enabling flexible memory structures for open and concurrent programs. To demonstrate the effectiveness of the nominal memory model, we develop a series of extensions of CompCert based on it. These extensions show that the nominal memory model 1) supports a general framework for verified compilation of C programs, 2) enables intuitive reasoning of compiler transformations on partial memory; and 3) enables modular reasoning about programs working with contextual memory. We also demonstrate that these extensions require limited changes to the original CompCert, making the verification techniques based on the nominal memory model easy to adopt.

Planning of the open-pit working edge positions by the periods of mining within the constraint programming paradigm

The work is aimed at solving the three-dimensional problem of finding the open-pit working edge positions by the periods of mining, taking into account the a priori specified productivity for the mineral and overburden. The proposed method uses a block model of a pit, where for each block its coordinates, the content of minerals in it, and the conditional initial value of the block are known. Also, a discounting function is set - a change in the total value of a block, depending on the period of its mining. The task is to find the distribution of blocks over mining periods that maximizes the total value of the blocks. Combinatorial search acceleration is achieved by representing a number of technological constraints in the form of global constraints.

The acquisition of variation: Arab migrants' acquisition of (ING) and Coronal Stop Deletion in Wellington

<p>This dissertation investigates the patterns of acquisition found among Arab migrants to Wellington for two stable variables: coronal stop deletion (CSD) and (ING). CSD is the alternation between retained and deleted final consonant clusters, i.e. /wɛst/ vs. /wɛs/ and (ING) is the realisation of the final nasal in unstressed word-final syllables i.e. /dɹaivɪŋ/ vs. /dɹaivɪn/. CSD is a phonological variable that is mainly conditioned by articulatory constraints while (ING) is a morpho-phonemic variable with syntactic conditioning as well. An emerging trend in variationist sociolinguistics is to study variation in non-native varieties by analysing how far non-native speaker (NNS) patterns of variation replicate constraints on variation found among native speakers (NS) of a target variety. This study applies variationist methods to investigate the following questions: 1. What are the linguistic and the non-linguistic constraints that condition variation in the production of (ING) and CSD among NS in the New Zealand Spoken English Database (NZSED) in Wellington? 2. What are the linguistic and the non-linguistic constraints that condition variation in the production of (ING) and CSD among Arab migrants in Wellington (AM)? 3. Based on the results for (1) and (2), is there any evidence for “transformation under transfer” (Meyerhoff, 2009a). Interpretation of the results is done in line with the so-called “three lines of evidence”, and considers significant and non-significant constraints, constraint hierarchies and rank ordering of constraints (Tagliamonte & Temple, 2005). I consider the proposition that AMs, of all ages, are prone to transformation under transfer of NS constraints on the variables CSD and (ING), mainly illustrating strong and weak transfer. It is expected that old and middle-aged AMs will have patterns different from those found among young AMs. I also consider the possibility that articulatory constraints may be more readily transformed by AMs into ethnolectal marking, whereas grammatical constraints may be more likely to be strongly transferred by AMs. Old and middle-aged AMs seem to be more likely to display strong transfer of NS constraints, but they do not seem to be using variation in the L2 stylistically. By contrast, young AMs stylistically use articulatory constraints to convey important social indexicalities. The results suggest that oold and middle-aged AMs with developing grammars are like NS children acquiring variation of their L1, in the sense that old and middle-aged AMs are sensitive, in both CSD and (ING), to dialect-specific constraints on variation as they display strong transfer of the highest ranked NS constraint, be it articulatory or grammatical in nature; they also seem to perceive NS frequencies of occurrence of variables. Old and middle-aged AMs have an advantage over NS-children in their cognitive abilities that enable them to apply global constraints on variation by filtering their previous exposure to English, to replicate grammatical constraints of the L2 variables. Old and middle-aged AMs also seem to replicate the articulatory constraints that are perceptually salient, or that can host L1 transfer. They sometimes innovate articulatory constraints that are meaningful to them probably because of the influence of their L1. Young AM, who have arrived in New Zealand at an age of six years or younger, would be expected to illustrate strong transfer for stable variables like CSD and (ING). The results, nevertheless, illustrate that although young AMs share the same significant constraints found among NS of NZSED, they have different rank orderings, internal hierarchies and frequency of variants. Young AM, unexpectedly, diverge from NS norms and exhibit weak transfer of NS articulatory constraints on CSD, while they show strong transfer of NS grammatical constraints for the variable (ING). I suggest that young AMs seem to be using articulatory constraints in the L2 stylistically, to convey important social indexicalities. In addition, young AMs seem to hold an intermediate status between NS of NZSED and first-generation AM. Like old and middle-aged AMs, they replicate global-grammatical constraints on (ING) with an internal hierarchy that follows the Labovian nominal-verbal continuum, rather than the local, internal hierarchy. This suggests that (ING), as a morphophonemic variable with syntactic interfaces, has less room for the stylistic use of variation patterns as a reflection of identity marking. Articulatory constraints may be more subject to L1 transfer and these may become a marker of ethnicity among a Second-generation of migrants.</p>

The acquisition of variation: Arab migrants' acquisition of (ING) and Coronal Stop Deletion in Wellington

<p>This dissertation investigates the patterns of acquisition found among Arab migrants to Wellington for two stable variables: coronal stop deletion (CSD) and (ING). CSD is the alternation between retained and deleted final consonant clusters, i.e. /wɛst/ vs. /wɛs/ and (ING) is the realisation of the final nasal in unstressed word-final syllables i.e. /dɹaivɪŋ/ vs. /dɹaivɪn/. CSD is a phonological variable that is mainly conditioned by articulatory constraints while (ING) is a morpho-phonemic variable with syntactic conditioning as well. An emerging trend in variationist sociolinguistics is to study variation in non-native varieties by analysing how far non-native speaker (NNS) patterns of variation replicate constraints on variation found among native speakers (NS) of a target variety. This study applies variationist methods to investigate the following questions: 1. What are the linguistic and the non-linguistic constraints that condition variation in the production of (ING) and CSD among NS in the New Zealand Spoken English Database (NZSED) in Wellington? 2. What are the linguistic and the non-linguistic constraints that condition variation in the production of (ING) and CSD among Arab migrants in Wellington (AM)? 3. Based on the results for (1) and (2), is there any evidence for “transformation under transfer” (Meyerhoff, 2009a). Interpretation of the results is done in line with the so-called “three lines of evidence”, and considers significant and non-significant constraints, constraint hierarchies and rank ordering of constraints (Tagliamonte & Temple, 2005). I consider the proposition that AMs, of all ages, are prone to transformation under transfer of NS constraints on the variables CSD and (ING), mainly illustrating strong and weak transfer. It is expected that old and middle-aged AMs will have patterns different from those found among young AMs. I also consider the possibility that articulatory constraints may be more readily transformed by AMs into ethnolectal marking, whereas grammatical constraints may be more likely to be strongly transferred by AMs. Old and middle-aged AMs seem to be more likely to display strong transfer of NS constraints, but they do not seem to be using variation in the L2 stylistically. By contrast, young AMs stylistically use articulatory constraints to convey important social indexicalities. The results suggest that oold and middle-aged AMs with developing grammars are like NS children acquiring variation of their L1, in the sense that old and middle-aged AMs are sensitive, in both CSD and (ING), to dialect-specific constraints on variation as they display strong transfer of the highest ranked NS constraint, be it articulatory or grammatical in nature; they also seem to perceive NS frequencies of occurrence of variables. Old and middle-aged AMs have an advantage over NS-children in their cognitive abilities that enable them to apply global constraints on variation by filtering their previous exposure to English, to replicate grammatical constraints of the L2 variables. Old and middle-aged AMs also seem to replicate the articulatory constraints that are perceptually salient, or that can host L1 transfer. They sometimes innovate articulatory constraints that are meaningful to them probably because of the influence of their L1. Young AM, who have arrived in New Zealand at an age of six years or younger, would be expected to illustrate strong transfer for stable variables like CSD and (ING). The results, nevertheless, illustrate that although young AMs share the same significant constraints found among NS of NZSED, they have different rank orderings, internal hierarchies and frequency of variants. Young AM, unexpectedly, diverge from NS norms and exhibit weak transfer of NS articulatory constraints on CSD, while they show strong transfer of NS grammatical constraints for the variable (ING). I suggest that young AMs seem to be using articulatory constraints in the L2 stylistically, to convey important social indexicalities. In addition, young AMs seem to hold an intermediate status between NS of NZSED and first-generation AM. Like old and middle-aged AMs, they replicate global-grammatical constraints on (ING) with an internal hierarchy that follows the Labovian nominal-verbal continuum, rather than the local, internal hierarchy. This suggests that (ING), as a morphophonemic variable with syntactic interfaces, has less room for the stylistic use of variation patterns as a reflection of identity marking. Articulatory constraints may be more subject to L1 transfer and these may become a marker of ethnicity among a Second-generation of migrants.</p>

IV Siberian Legal Forum: State and Law in the Context of Global Constraints

.

Quantum-accelerated constraint programming

Constraint programming (CP) is a paradigm used to model and solve constraint satisfaction and combinatorial optimization problems. In CP, problems are modeled with constraints that describe acceptable solutions and solved with backtracking tree search augmented with logical inference. In this paper, we show how quantum algorithms can accelerate CP, at both the levels of inference and search. Leveraging existing quantum algorithms, we introduce a quantum-accelerated filtering algorithm for the alldifferent global constraint and discuss its applicability to a broader family of global constraints with similar structure. We propose frameworks for the integration of quantum filtering algorithms within both classical and quantum backtracking search schemes, including a novel hybrid classical-quantum backtracking search method. This work suggests that CP is a promising candidate application for early fault-tolerant quantum computers and beyond.

Subshifts and colorings on ascending HNN-extensions of finitely generated abelian groups

For an ascending HNN-extension $G*_{\psi }$ of a finitely generated abelian group G, we study how a synchronization between the geometry of the group and weak periodicity of a configuration in $\mathcal {A}^{G*_{\psi }}$ forces global constraints on it, as well as in subshifts containing it. A particular case are Baumslag–Solitar groups $\mathrm {BS}(1,N)$ , $N\ge 2$ , for which our results imply that a $\mathrm {BS}(1,N)$ -subshift of finite type which contains a configuration with period $a^{N^\ell }\!, \ell \ge 0$ , must contain a strongly periodic configuration with monochromatic $\mathbb {Z}$ -sections. Then we study proper n-colorings, $n\ge 3$ , of the (right) Cayley graph of $\mathrm {BS}(1,N)$ , estimating the entropy of the associated subshift together with its mixing properties. We prove that $\mathrm {BS}(1,N)$ admits a frozen n-coloring if and only if $n=3$ . We finally suggest generalizations of the latter results to n-colorings of ascending HNN-extensions of finitely generated abelian groups.

Drought Stress Alleviation by Potassium-Nitrate-Containing Chitosan/Montmorillonite Microparticles Confers Changes in Spinacia oleracea L.

Drought and low amounts of mineral nutrients in the soil are the two leading global constraints in arid and semiarid regions. Their detrimental effects on soils and crops can be alleviated by applying controlled release and biodegradable fertilizers to better and sustain the crops. On a global scale, spinach (Spinacia oleracea L.) is an essential leafy green vegetable that is biologically considered a reliable source of essential nutrients and minerals for human health. A comprehensive approach is needed to manage water stress to mitigate the impacts of stress-caused damage and to examine this for better and increased plant production. An experiment was conducted using potassium-nitrate-containing chitosan/montmorillonite microparticles (150 mg) under mild and severe drought stress (MDS: 50% and SDS: 35% FC, respectively). The treatments include control (no KNO3 and 70% FC as normal irrigation (NI)), KNO3 + NI, 50% FC as mild drought stress (MDS), KNO3 + MDS, 35% FC as severe drought stress (SDS) and KNO3 + SDS. Results revealed that drought stress decreased all studied physiological parameters and increased oxidative stress indicators in spinach. Applying KN significantly increased root (122%) and shoot length (4%), shoot fresh weight (32%) and shoot dry weight (71%), chlorophyll a (88%), carotenoids (39%), total soluble proteins (50%), soluble sugars (51%), potassium (80%), and phosphorous (32%) concentrations over No KN at severe drought. While stress indicators, like glycine betaine, malondialdehyde, hydrogen peroxide, electrolyte leakage, peroxidase, superoxide dismutase, and ascorbic acid levels, were increased in stress. Treatment KN was proved efficient and effective in improving spinach physiological status in both MDS and SDS.

New insights into large-scale trends of apparent organic matter reactivity in marine sediments and patterns of benthic carbon transformation

Constraining the mechanisms controlling organic matter (OM) reactivity and, thus, degradation, preservation, and burial in marine sediments across spatial and temporal scales is key to understanding carbon cycling in the past, present, and future. However, we still lack a detailed quantitative understanding of what controls OM reactivity in marine sediments and, consequently, a general framework that would allow model parametrization in data-poor areas. To fill this gap, we quantify apparent OM reactivity (i.e. OM degradation rate constants) by extracting reactive continuum model (RCM) parameters (a and v, which define the shape and scale of OM reactivity profiles, respectively) from observed benthic organic carbon and sulfate dynamics across 14 contrasting depositional settings distributed over five distinct benthic provinces. We further complement the newly derived parameter set with a compilation of 37 previously published RCM a and v estimates to explore large-scale trends in OM reactivity. Our analysis shows that the large-scale variability in apparent OM reactivity is largely driven by differences in parameter a (10−3–107) with a high frequency of values in the range 100–104 years. In contrast, and in broad agreement with previous findings, inversely determined v values fall within a narrow range (0.1–0.2). Results also show that the variability in parameter a and, thus, in apparent OM reactivity is a function of the whole depositional environment, rather than traditionally proposed, single environmental controls (e.g. water depth, sedimentation rate, OM fluxes). Thus, we caution against the simplifying use of a single environmental control for predicting apparent OM reactivity beyond a specific local environmental context (i.e. well-defined geographic scale). Additionally, model results indicate that, while OM fluxes exert a dominant control on depth-integrated OM degradation rates across most depositional environments, apparent OM reactivity becomes a dominant control in depositional environments that receive exceptionally reactive OM. Furthermore, model results show that apparent OM reactivity exerts a key control on the relative significance of OM degradation pathways, the redox zonation of the sediment, and rates of anaerobic oxidation of methane. In summary, our large-scale assessment (i) further supports the notion of apparent OM reactivity as a dynamic ecosystem property, (ii) consolidates the distributions of RCM parameters, and (iii) provides quantitative constraints on how OM reactivity governs benthic biogeochemical cycling and exchange. Therefore, it provides important global constraints on the most plausible range of RCM parameters a and v and largely alleviates the difficulty of determining OM reactivity in RCM by constraining it to only one variable, i.e. the parameter a. It thus represents an important advance for model parameterization in data-poor areas.