2,514 research outputs found
The IO and OI hierarchies revisited
International audienceWe study languages of λ-terms generated by IO and OI unsafe grammars. These languages can be used to model meaning representations in the formal semantics of natural languages following the tradition of Montague [25]. Using techniques pertaining to the denotational semantics of the simply typed λ-calculus, we show that the emptiness and membership problems for both types of grammars are decidable. In the course of the proof of the decidability results for OI, we identify a decidable variant of the λ-definability problem, and prove a stronger form of Statman's finite completeness Theorem [35]
The IO and OI hierarchies revisited
International audienceWe study languages of lambda-terms generated by IO and OI unsafe grammars. These languages can be used to model meaning representations in the formal semantics of natural languages following the tradition of Montague. Using techniques pertaining to the denotational semantics of the simply typed lambda-calculus, we show that the emptiness and membership problems for both types of grammars are decidable. In the course of the proof of the decidability results for OI, we identify a decidable variant of the lambda-definability problem, and prove a stronger form of Statman's finite completeness Theorem
Do Multinationals Transplant their Business Model?
What determines whether or not multinational firms transplant their mode of organisation to other countries? We embed the theory of knowledge hierarchies in an industry equilibrium model of monopolistic competition to examine how the economic environment may affect the decision of a multinational firm about transplanting its business organisation to other countries. We test the theory with original and matched parent and affiliate data on the internal organisation of 660 Austrian and German multinational firms and 2200 of their affiliate firms in Eastern Europe. We find that three factors stand out in promoting the multinational firm’s decision to transplant the business model to the affiliate firm in the host country: a competitive host market, the corporate culture of the multinational firm, and when an innovative technology is transferred to the host country. These factors increase the respective probabilities of organisational transfer by 18.5 percentage points, 37, and 31 percentage points
On Characterizing the Data Movement Complexity of Computational DAGs for Parallel Execution
Technology trends are making the cost of data movement increasingly dominant,
both in terms of energy and time, over the cost of performing arithmetic
operations in computer systems. The fundamental ratio of aggregate data
movement bandwidth to the total computational power (also referred to the
machine balance parameter) in parallel computer systems is decreasing. It is
there- fore of considerable importance to characterize the inherent data
movement requirements of parallel algorithms, so that the minimal architectural
balance parameters required to support it on future systems can be well
understood. In this paper, we develop an extension of the well-known red-blue
pebble game to develop lower bounds on the data movement complexity for the
parallel execution of computational directed acyclic graphs (CDAGs) on parallel
systems. We model multi-node multi-core parallel systems, with the total
physical memory distributed across the nodes (that are connected through some
interconnection network) and in a multi-level shared cache hierarchy for
processors within a node. We also develop new techniques for lower bound
characterization of non-homogeneous CDAGs. We demonstrate the use of the
methodology by analyzing the CDAGs of several numerical algorithms, to develop
lower bounds on data movement for their parallel execution
The Diagonal Problem for Higher-Order Recursion Schemes is Decidable
A non-deterministic recursion scheme recognizes a language of finite trees.
This very expressive model can simulate, among others, higher-order pushdown
automata with collapse. We show decidability of the diagonal problem for
schemes. This result has several interesting consequences. In particular, it
gives an algorithm that computes the downward closure of languages of words
recognized by schemes. In turn, this has immediate application to separability
problems and reachability analysis of concurrent systems.Comment: technical report; to appear in LICS'1
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