Abstract Current generalizations of the central ideas of single-objective branch-and-bound to the multiobjective setting do not seem to follow their train of thought all the way. The present paper complements the various suggestions for generalizations of partial lower bounds and of overall upper bounds by general constructions for overall lower bounds from partial lower bounds, and by the corresponding termination criteria and node selection steps. In particular, our branch-and-bound concept employs a new enclosure of the set of nondominated points by a union of boxes. On this occasion we also suggest a new discarding test based on a linearization technique. We provide a convergence proof for our general branch-and-bound framework and illustrate the results with numerical examples.

In HCI, adult concerns about technologies for children have been studied extensively. However, less is known about what children themselves find concerning in everyday technologies. We examine children's technology-related fears by probing their use of the colloquial term "creepy." To understand children's perceptions of "creepy technologies," we conducted four participatory design sessions with children (ages 7 - 11) to design and evaluate creepy technologies, followed by interviews with the same children. We found that children's fear reactions emphasized physical harm and threats to their relationships (particularly with attachment figures). The creepy signals from technology the children described include: deception, lack of control, mimicry, ominous physical appearance, and unpredictability. Children acknowledged trusted adults will mediate the relationship between creepy technology signals and fear responses. Our work contributes a close examination of what children mean when they say a technology is "creepy." By treating these concerns as principal design considerations, developers can build systems that are more transparent about the risks they produce and more sensitive to the fears they may unintentionally raise.