Abstract
Causality tracking mechanisms, such as vector clocks and version vectors, rely on mappings from globally unique identifiers to integer counters. In a system with a well known set of entities these ids can be preconfigured and given distinct positions in a vector or distinct names in a mapping. Id management is more problematic in dynamic systems, with large and highly variable number of entities, being worsened when network partitions occur. Present solutions for causality tracking are not appropriate to these increasingly common scenarios. In this paper we introduce Interval Tree Clocks, a novel causality tracking mechanism that can be used in scenarios with a dynamic number of entities, allowing a completely decentralized creation of processes/replicas without need for global identifiers or global coordination. The mechanism has a variable size representation that adapts automatically to the number of existing entities, growing or shrinking appropriately. The representation is so compact that the mechanism can even be considered for scenarios with a fixed number of entities, which makes it a general substitute for vector clocks and version vectors.

Abstract
Computational Design (CD) is a paradigm where both program design and program synthesis are computations. CD merges Model Driven Engineering (MDE) which synthesizes programs by transforming models, with Software Product Lines (SPL) where programs are synthesized by composing trans format ions called features. In this paper, basic relationships between MDE and SPL are explored using the language of modern mathematics.

Abstract
Denotational semantics is a powerful technique to formally de. ne programming languages. However, language constructs are not always orthogonal, so many semantic equations in a definition may have to be aware of unrelated constructs semantics. Current approaches for modularity in this formalism do not address this problem, providing, for this reason, tangled semantic definitions. This paper proposes an incremental approach for denotational semantic specifications, in which each step can either add new features or adapt existing equations, by means of a formal language based on function transformation and aspect weaving.

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