Events in an online social network can be categorized roughly into endogenous
events, where users just respond to the actions of their neighbors within the
network, or exogenous events, where users take actions due to drives external
to the network. How much external drive should be provided to each user, such
that the network activity can be steered towards a target state? In this paper,
we model social events using multivariate Hawkes processes, which can capture
both endogenous and exogenous event intensities, and derive a time dependent
linear relation between the intensity of exogenous events and the overall
network activity. Exploiting this connection, we develop a convex optimization
framework for determining the required level of external drive in order for the
network to reach a desired activity level. We experimented with event data
gathered from Twitter, and show that our method can steer the activity of the
network more accurately than alternatives.

利用多元 Hawkes 过程模型和凸优化框架来在在线社交网络中确定外部驱动作用，以控制网络活动达到预期状态。

通过激励用户塑造社交活动

Shaping Social Activity by Incentivizing Users

We formalize a simple but natural subclass of service domains for relational
planning problems with object-centered, independent exogenous events and
additive rewards capturing, for example, problems in inventory control.
Focusing on this subclass, we present a new symbolic planning algorithm which
is the first algorithm that has explicit performance guarantees for relational
MDPs with exogenous events. In particular, under some technical conditions, our
planning algorithm provides a monotonic lower bound on the optimal value
function. To support this algorithm we present novel evaluation and reduction
techniques for generalized first order decision diagrams, a knowledge
representation for real-valued functions over relational world states. Our
planning algorithm uses a set of focus states, which serves as a training set,
to simplify and approximate the symbolic solution, and can thus be seen to
perform learning for planning. A preliminary experimental evaluation
demonstrates the validity of our approach.

本文介绍了一种符号规划算法，该算法是面向以对象为中心、独立的外部事件和捕捉库存控制等问题的服务域的，该算法具有明确的关于外部事件的关系 MDP 的性能保证，在某些技术条件下，我们的规划算法提供了关于最优值函数的单调下界。为了支持这种算法，我们使用广义一阶决策图作为知识表示，提出了新颖的评估和约简技术。我们的规划算法使用一组焦点状态，这组状态作为一个训练集，简化和近似符号解，并且可以被视为执行规划的学习。一项初步的实验评估证明了这种方法的有效性。