34 research outputs found
Learning Chordal Markov Networks via Branch and Bound
We present a new algorithmic approach for the task of finding a chordal Markov network structure that maximizes a given scoring function. The algorithm is based on branch and bound and integrates dynamic programming for both domain pruning and for obtaining strong bounds for search-space pruning. Empirically, we show that the approach dominates in terms of running times a recent integer programming approach (and thereby also a recent constraint optimization approach) for the problem. Furthermore, our algorithm scales at times further with respect to the number of variables than a state-of-the-art dynamic programming algorithm for the problem, with the potential of reaching 20 variables and at the same time circumventing the tight exponential lower bounds on memory consumption of the pure dynamic programming approach.Peer reviewe
Making the invisible visible:Underwater Maltaâa virtual museum for submerged cultural heritage
The seabed can be considered as the worldâs largest museum, and underwater sites exâ
plored and studied so far provide priceless information on human interaction with the sea. In recogâ
nition of the importance of this cultural resource, UNESCO, in its 2001 Convention on the Protection
of the Underwater Cultural Heritage, determined that objects/sites should be preserved in situ,
whilst also advocating for public access and sharing. The implementation of these principles is not
without difficulties. Some states have opened up underwater sites to the publicâmainly through
diving, yet the vast majority of the worldâs population does not dive. In Malta, 7000 years of human
occupation is reflected in and on the landscape, and recent offshore surveys show that the islandsâ
long and complex history has also left an indelible mark on the seabed. Besides difficulties related
to their protection and management, these sites also present a challenge with regard to sharing and
communicating. Recent advances in underwater imaging and processing software have accelerated
the development of 3D photogrammetry of submerged sites and the idea for a virtual museum was
born. The virtual museum, UnderwaterMalta, was created out of a need to share the plethora of
underwater sites located on the seabed of the Maltese Islands. A multitude of digital tools are used
to share and communicate these sites, offering visitors a dry dive into submerged sites that would
otherwise remain invisible to the vast majority of the public. This paper discusses the basic principle
of the sharing of underwater cultural heritage and the difficulties that beset the implementation of
such a principle. A detailed explanation and evaluation of the methods used to gather the raw data
needed is set in the context of the particular and unique working conditions related to deep water
sites. The workings of this paper are based on firstâhand experiences garnered through the recordâ
ing of numerous wrecks over the years and the creation and launch of The Virtual MuseumâUnderâ
water Maltaâa comprehensive virtual museum specifically built for âdisplayingâ underwater arâ
chaeological sites that are otherwise invisible to the general public.peer-reviewe
Learning Optimal Causal Graphs with Exact Search
Peer reviewe
Human in vivo liver and tumor bioimpedance measured with biopsy needle
acceptedVersionPeer reviewe