2,761 research outputs found
Near-Optimally Teaching the Crowd to Classify
How should we present training examples to learners to teach them
classification rules? This is a natural problem when training workers for
crowdsourcing labeling tasks, and is also motivated by challenges in
data-driven online education. We propose a natural stochastic model of the
learners, modeling them as randomly switching among hypotheses based on
observed feedback. We then develop STRICT, an efficient algorithm for selecting
examples to teach to workers. Our solution greedily maximizes a submodular
surrogate objective function in order to select examples to show to the
learners. We prove that our strategy is competitive with the optimal teaching
policy. Moreover, for the special case of linear separators, we prove that an
exponential reduction in error probability can be achieved. Our experiments on
simulated workers as well as three real image annotation tasks on Amazon
Mechanical Turk show the effectiveness of our teaching algorithm
Teaching Categories to Human Learners with Visual Explanations
We study the problem of computer-assisted teaching with explanations.
Conventional approaches for machine teaching typically only provide feedback at
the instance level e.g., the category or label of the instance. However, it is
intuitive that clear explanations from a knowledgeable teacher can
significantly improve a student's ability to learn a new concept. To address
these existing limitations, we propose a teaching framework that provides
interpretable explanations as feedback and models how the learner incorporates
this additional information. In the case of images, we show that we can
automatically generate explanations that highlight the parts of the image that
are responsible for the class label. Experiments on human learners illustrate
that, on average, participants achieve better test set performance on
challenging categorization tasks when taught with our interpretable approach
compared to existing methods
Becoming the Expert - Interactive Multi-Class Machine Teaching
Compared to machines, humans are extremely good at classifying images into
categories, especially when they possess prior knowledge of the categories at
hand. If this prior information is not available, supervision in the form of
teaching images is required. To learn categories more quickly, people should
see important and representative images first, followed by less important
images later - or not at all. However, image-importance is individual-specific,
i.e. a teaching image is important to a student if it changes their overall
ability to discriminate between classes. Further, students keep learning, so
while image-importance depends on their current knowledge, it also varies with
time.
In this work we propose an Interactive Machine Teaching algorithm that
enables a computer to teach challenging visual concepts to a human. Our
adaptive algorithm chooses, online, which labeled images from a teaching set
should be shown to the student as they learn. We show that a teaching strategy
that probabilistically models the student's ability and progress, based on
their correct and incorrect answers, produces better 'experts'. We present
results using real human participants across several varied and challenging
real-world datasets.Comment: CVPR 201
Teaching Inverse Reinforcement Learners via Features and Demonstrations
Learning near-optimal behaviour from an expert's demonstrations typically
relies on the assumption that the learner knows the features that the true
reward function depends on. In this paper, we study the problem of learning
from demonstrations in the setting where this is not the case, i.e., where
there is a mismatch between the worldviews of the learner and the expert. We
introduce a natural quantity, the teaching risk, which measures the potential
suboptimality of policies that look optimal to the learner in this setting. We
show that bounds on the teaching risk guarantee that the learner is able to
find a near-optimal policy using standard algorithms based on inverse
reinforcement learning. Based on these findings, we suggest a teaching scheme
in which the expert can decrease the teaching risk by updating the learner's
worldview, and thus ultimately enable her to find a near-optimal policy.Comment: NeurIPS'2018 (extended version
Iterative Classroom Teaching
We consider the machine teaching problem in a classroom-like setting wherein
the teacher has to deliver the same examples to a diverse group of students.
Their diversity stems from differences in their initial internal states as well
as their learning rates. We prove that a teacher with full knowledge about the
learning dynamics of the students can teach a target concept to the entire
classroom using O(min{d,N} log(1/eps)) examples, where d is the ambient
dimension of the problem, N is the number of learners, and eps is the accuracy
parameter. We show the robustness of our teaching strategy when the teacher has
limited knowledge of the learners' internal dynamics as provided by a noisy
oracle. Further, we study the trade-off between the learners' workload and the
teacher's cost in teaching the target concept. Our experiments validate our
theoretical results and suggest that appropriately partitioning the classroom
into homogenous groups provides a balance between these two objectives.Comment: AAAI'19 (extended version
Enabling Robots to Communicate their Objectives
The overarching goal of this work is to efficiently enable end-users to
correctly anticipate a robot's behavior in novel situations. Since a robot's
behavior is often a direct result of its underlying objective function, our
insight is that end-users need to have an accurate mental model of this
objective function in order to understand and predict what the robot will do.
While people naturally develop such a mental model over time through observing
the robot act, this familiarization process may be lengthy. Our approach
reduces this time by having the robot model how people infer objectives from
observed behavior, and then it selects those behaviors that are maximally
informative. The problem of computing a posterior over objectives from observed
behavior is known as Inverse Reinforcement Learning (IRL), and has been applied
to robots learning human objectives. We consider the problem where the roles of
human and robot are swapped. Our main contribution is to recognize that unlike
robots, humans will not be exact in their IRL inference. We thus introduce two
factors to define candidate approximate-inference models for human learning in
this setting, and analyze them in a user study in the autonomous driving
domain. We show that certain approximate-inference models lead to the robot
generating example behaviors that better enable users to anticipate what it
will do in novel situations. Our results also suggest, however, that additional
research is needed in modeling how humans extrapolate from examples of robot
behavior.Comment: RSS 201
Interactive Teaching Algorithms for Inverse Reinforcement Learning
We study the problem of inverse reinforcement learning (IRL) with the added
twist that the learner is assisted by a helpful teacher. More formally, we
tackle the following algorithmic question: How could a teacher provide an
informative sequence of demonstrations to an IRL learner to speed up the
learning process? We present an interactive teaching framework where a teacher
adaptively chooses the next demonstration based on learner's current policy. In
particular, we design teaching algorithms for two concrete settings: an
omniscient setting where a teacher has full knowledge about the learner's
dynamics and a blackbox setting where the teacher has minimal knowledge. Then,
we study a sequential variant of the popular MCE-IRL learner and prove
convergence guarantees of our teaching algorithm in the omniscient setting.
Extensive experiments with a car driving simulator environment show that the
learning progress can be speeded up drastically as compared to an uninformative
teacher.Comment: IJCAI'19 paper (extended version
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