24,282 research outputs found
Mining top-k granular association rules for recommendation
Recommender systems are important for e-commerce companies as well as
researchers. Recently, granular association rules have been proposed for
cold-start recommendation. However, existing approaches reserve only globally
strong rules; therefore some users may receive no recommendation at all. In
this paper, we propose to mine the top-k granular association rules for each
user. First we define three measures of granular association rules. These are
the source coverage which measures the user granule size, the target coverage
which measures the item granule size, and the confidence which measures the
strength of the association. With the confidence measure, rules can be ranked
according to their strength. Then we propose algorithms for training the
recommender and suggesting items to each user. Experimental are undertaken on a
publicly available data set MovieLens. Results indicate that the appropriate
setting of granule can avoid over-fitting and at the same time, help obtaining
high recommending accuracy.Comment: 12 pages, 5 figures, submitted to Advances in Granular Computing and
Advances in Rough Sets, 2013. arXiv admin note: substantial text overlap with
arXiv:1305.137
Phase transitions and spin excitations of spin-1 bosons in optical lattice
We investigate ground state properties of spin-1 bosonic system trapped in
optical lattice with extended standard basis operator (SBO) method. For both
ferromagnetic () systems, we
analytically figure out the symmetry properties in Mott-insulator and
superfluid phases, which would provide a deeper insight into the MI-SF phase
transition process. Then by applying self-consistent approach to the method, we
include the effect of quantum and thermal fluctuations and derive the MI-SF
transition phase diagram, which is in quantitative agreement with recent
Monte-Carlo simulation at zero temperature, and at finite temperature, we find
the underestimation of finite-temperature-effect in the mean-field
approximation method. If we further consider the spin excitations in the
insulating states of spin-1 system in external field, distinct spin phases are
expected. Therefore, in the Mott lobes with and atoms per site, we
give analytical and numerical boundaries of the singlet, nematic, partially
magnetic and ferromagnetic phases in the magnetic phase diagrams.Comment: 14 pages, 6 figure
- …