2 research outputs found
Predicting Temporal Sets with Deep Neural Networks
Given a sequence of sets, where each set contains an arbitrary number of
elements, the problem of temporal sets prediction aims to predict the elements
in the subsequent set. In practice, temporal sets prediction is much more
complex than predictive modelling of temporal events and time series, and is
still an open problem. Many possible existing methods, if adapted for the
problem of temporal sets prediction, usually follow a two-step strategy by
first projecting temporal sets into latent representations and then learning a
predictive model with the latent representations. The two-step approach often
leads to information loss and unsatisfactory prediction performance. In this
paper, we propose an integrated solution based on the deep neural networks for
temporal sets prediction. A unique perspective of our approach is to learn
element relationship by constructing set-level co-occurrence graph and then
perform graph convolutions on the dynamic relationship graphs. Moreover, we
design an attention-based module to adaptively learn the temporal dependency of
elements and sets. Finally, we provide a gated updating mechanism to find the
hidden shared patterns in different sequences and fuse both static and dynamic
information to improve the prediction performance. Experiments on real-world
data sets demonstrate that our approach can achieve competitive performances
even with a portion of the training data and can outperform existing methods
with a significant margin.Comment: 9 pages, 6 figures, Proceedings of the 26th ACM SIGKDD Conference on
Knowledge Discovery and Data Mining (KDD '2020
Masked and Swapped Sequence Modeling for Next Novel Basket Recommendation in Grocery Shopping
Next basket recommendation (NBR) is the task of predicting the next set of
items based on a sequence of already purchased baskets. It is a recommendation
task that has been widely studied, especially in the context of grocery
shopping. In next basket recommendation (NBR), it is useful to distinguish
between repeat items, i.e., items that a user has consumed before, and explore
items, i.e., items that a user has not consumed before. Most NBR work either
ignores this distinction or focuses on repeat items. We formulate the next
novel basket recommendation (NNBR) task, i.e., the task of recommending a
basket that only consists of novel items, which is valuable for both real-world
application and NBR evaluation. We evaluate how existing NBR methods perform on
the NNBR task and find that, so far, limited progress has been made w.r.t. the
NNBR task. To address the NNBR task, we propose a simple bi-directional
transformer basket recommendation model (BTBR), which is focused on directly
modeling item-to-item correlations within and across baskets instead of
learning complex basket representations. To properly train BTBR, we propose and
investigate several masking strategies and training objectives: (i) item-level
random masking, (ii) item-level select masking, (iii) basket-level all masking,
(iv) basket-level explore masking, and (v) joint masking. In addition, an
item-basket swapping strategy is proposed to enrich the item interactions
within the same baskets. We conduct extensive experiments on three open
datasets with various characteristics. The results demonstrate the
effectiveness of BTBR and our masking and swapping strategies for the NNBR
task. BTBR with a properly selected masking and swapping strategy can
substantially improve NNBR performance.Comment: To appear at RecSys'2