1,556 research outputs found
Michael Porter's Cluster Theory as a local and regional development tool â the rise and fall of cluster policy in the UK
There has been much written on industrial agglomeration, but it is Michael Porterâs cluster theory, above all others, which has come to dominate local and regional economic development policy. His work has been adopted by the OECD, EU, national and local governments the world over. He and his consultancy group have led reviews of national economic growth strategies in dozens of countries. This rise to prominence, however, is in the face of widespread critique from academics. Cluster theoryâs theoretical foundations, its methodological approach and practical implementation have all been unpicked, leading some to label little more than a successful brand riding the wave of new regionalist fashions. Despite libraries of incredibly useful books and articles on clusters, there remains an absence of work which interrogates the translation of clusters into, and then through local and national policy. The aim of this article is to go some way to remedying the situation by examining the influence of Porterâs cluster theory charted through an examin- ation of UK regional development policy in the 1990s and 2000s. To help map the journey of clusters into and through UK economic development policy actor-network theory is adopted as an explanatory framework
Fix Your Types
When using existing ACL2 datatype frameworks, many theorems require type
hypotheses. These hypotheses slow down the theorem prover, are tedious to
write, and are easy to forget. We describe a principled approach to types that
provides strong type safety and execution efficiency while avoiding type
hypotheses, and we present a library that automates this approach. Using this
approach, types help you catch programming errors and then get out of the way
of theorem proving.Comment: In Proceedings ACL2 2015, arXiv:1509.0552
Verified AIG Algorithms in ACL2
And-Inverter Graphs (AIGs) are a popular way to represent Boolean functions
(like circuits). AIG simplification algorithms can dramatically reduce an AIG,
and play an important role in modern hardware verification tools like
equivalence checkers. In practice, these tricky algorithms are implemented with
optimized C or C++ routines with no guarantee of correctness. Meanwhile, many
interactive theorem provers can now employ SAT or SMT solvers to automatically
solve finite goals, but no theorem prover makes use of these advanced,
AIG-based approaches.
We have developed two ways to represent AIGs within the ACL2 theorem prover.
One representation, Hons-AIGs, is especially convenient to use and reason
about. The other, Aignet, is the opposite; it is styled after modern AIG
packages and allows for efficient algorithms. We have implemented functions for
converting between these representations, random vector simulation, conversion
to CNF, etc., and developed reasoning strategies for verifying these
algorithms.
Aside from these contributions towards verifying AIG algorithms, this work
has an immediate, practical benefit for ACL2 users who are using GL to
bit-blast finite ACL2 theorems: they can now optionally trust an off-the-shelf
SAT solver to carry out the proof, instead of using the built-in BDD package.
Looking to the future, it is a first step toward implementing verified AIG
simplification algorithms that might further improve GL performance.Comment: In Proceedings ACL2 2013, arXiv:1304.712
The accidental youth club: skateboarding in NewcastleGateshead.
Skateboarders re-invent and interrogate the physical structure of cityscapes as they use spaces, buildings and objects for skating. However skaters are routinely regarded by the civic and business interests who dominate city centre planning and regeneration as, at best, a nuisance and at worst an unruly and dangerous blight. This paper reports findings from a research project involving skaters which begins to unpick this stereotype. A participatory methodology combining mapping, interviews and observation was used to identify spots used by skaters in Newcastle and Gateshead (North East England). The key spots were characterized using Woolley & Johnsâ(2001) criteria: trickability, accessibility, sociability and compatibility. Findings reveal two further 12 factors â temporal and relational dimensions â are crucial the journeys skaters embark on. Sociability was the one constant factor defining favoured spots. The study revealed a sociable, entrepreneurial, creative skate scene. Far from being a problem the skaters add to the social capital of the cityscape. Our findings suggest rather than designing out skaters from the city the civic authorities should work with skaters to sustain their scene as a positive benefit to city regeneration
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