Step-Indexed Relational Reasoning for Countable Nondeterminism

Programming languages with countable nondeterministic choice are computationally interesting since countable nondeterminism arises when modeling fairness for concurrent systems. Because countable choice introduces non-continuous behaviour, it is well-known that developing semantic models for programming languages with countable nondeterminism is challenging. We present a step-indexed logical relations model of a higher-order functional programming language with countable nondeterminism and demonstrate how it can be used to reason about contextually defined may- and must-equivalence. In earlier step-indexed models, the indices have been drawn from {\omega}. Here the step-indexed relations for must-equivalence are indexed over an ordinal greater than {\omega}

Hydromorphological classification of Slovenian rivers

This paper provides an overview of hydromorphological and related classifications of rivers in Slovenia and elsewhere. The Rosgen classification is presented in greater detail; it was used in the study as the basis for developing the first Slovenian hydromorphological classification. A hydromorphological survey form was designed to classify rivers and used in the office and field survey of hydromorphological variables in the 95 river sections selected in Slovenia. In the river sections studied, hydromorphological types were identified by analyzing the co-occurrence of selected hydromorphological variables. This method was used to identify 10 hydromorphological types, for which the main hydromorphological features are presented in this paper. Based on the results of the first hydromorphological classification of Slovenian rivers, guidelines are provided for future work

Vodno načrtovanje in načrti upravljanja voda

Direktiva 2000/60/ES – vodna direktiva – določa skupen evropski pristop k trajnostnemu upravljanju površinskih in podzemnih voda. Pri tem upošteva tako človekove vplive na vodno okolje kot tudi socioekonomske implikacije vplivov in predvidenih preventivnih in sanacijskih ukrepov. Okoljski cilj vodne direktive je doseči dobro stanje vseh voda na območju EU do leta 2015, s pogojnimi izjemami pa do leta 2021, oziroma najkasneje do leta 2027. Pri tem je temeljno izhodišče integralni vodnonačrtovalski pristop, t.j. integracija vseh dejavnikov vodnega okolja v načrte upravljanja voda ter informiranost in sodelovanje javnosti

Denotational semantics for guarded dependent type theory

We present a new model of Guarded Dependent Type Theory (GDTT), a type theory with guarded recursion and multiple clocks in which one can program with, and reason about coinductive types. Productivity of recursively defined coinductive programs and proofs is encoded in types using guarded recursion, and can therefore be checked modularly, unlike the syntactic checks implemented in modern proof assistants. The model is based on a category of covariant presheaves over a category of time objects, and quantification over clocks is modelled using a presheaf of clocks. To model the clock irrelevance axiom, crucial for programming with coinductive types, types must be interpreted as presheaves orthogonal to the object of clocks. In the case of dependent types, this translates to a lifting condition similar to the one found in homotopy theoretic models of type theory, but here with an additional requirement of uniqueness of lifts. Since the universes defined by the standard Hofmann-Streicher construction in this model do not satisfy this property, the universes in GDTT must be indexed by contexts of clock variables. We show how to model these universes in such a way that inclusions of clock contexts give rise to inclusions of universes commuting with type operations on the nose.Comment: This is the third version of the paper representing a minor revision over the second version. The paper has 40 page

Guarded Cubical Type Theory: Path Equality for Guarded Recursion

This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning with coinductive types. We wish to implement GDTT with decidable type-checking, while still supporting non-trivial equality proofs that reason about the extensions of guarded recursive constructions. CTT is a variation of Martin-L\"of type theory in which the identity type is replaced by abstract paths between terms. CTT provides a computational interpretation of functional extensionality, is conjectured to have decidable type checking, and has an implemented type-checker. Our new type theory, called guarded cubical type theory, provides a computational interpretation of extensionality for guarded recursive types. This further expands the foundations of CTT as a basis for formalisation in mathematics and computer science. We present examples to demonstrate the expressivity of our type theory, all of which have been checked using a prototype type-checker implementation, and present semantics in a presheaf category.Comment: 17 pages, to be published in proceedings of CSL 201

Dependence of mechanical properties on Cu content in AlSi9Cu3(Fe) alloy

Legura aluminija AlSi9Cu3(Fe) je jedna od najčešće korištenih aluminijevih legura jer je njezina primjena temeljena na dobrim mehaničkim svojstvima. U proizvodnji često nastaju odstupanja od maksimalno dopuštenih granica pojedinih legirajućih elemenata, posebice bakra. Budući da mehanička svojstva gotovih proizvoda iz ovih legura ovise o sadržaju bakra, različiti udjeli bakra su dodavani osnovnoj leguri, a sadržaj kemijskih elemenata je praćen pomoću optičkog spektrometra, ispitivanja tvrdoće HB i mjerenja vlačne čvrstoće. Uz ova ispitivanja, analiziran je i utjecaj bakra na oksidacijska svojstva i korozijsku postojanost. Najbolji rezultati dobiveni su za 3 wt. % udjela Cu.AlSi9Cu3(Fe) aluminium alloy is one of the most commonly used casting aluminium alloys because their utility is based on good mechanical properties. Production often leads to deviations of maximum levels for certain alloying elements, particularly copper. Since mechanical properties of the final products of these alloys strongly depend on the concentration of copper in the alloy, various concentrations of copper were added to the basic alloy whereas the chemical composition was monitored using an optical emission spectrometer, measuring Brinell hardness and doing tensile tests. Moreover, the impacts of copper on oxidizing and corrosion resistance of the experimental alloys were analysed. The alloy with 3 wt. % Cu showed the best results

Permanently protected agricultural land and the location of water sources suitable for irrigation

To aid the formation of the suggested areas of\ud permanently protected agricultural land, an allocation\ud algorithm was developed and used to establish the\ud irrigation water use potential of surface waters\ud streams, reservoirs, groundwater and treated municipal\ud wastewater, with the case study area of Slovenia.\ud The result is a map of the irrigation water use\ud potential, regarding the location and water source\ud use suitability for irrigation. The map shows areas\ud where the permanent protection of agricultural land\ud would be either most suitable either least suitable.\ud The appearance of the map depends on several water\ud management aspects, i.e. water demand management,\ud water use administration, the targeted management\ud of water infrastructure and the development of new\ud water sources