Abstract: In a general aspect, a system can include a leader device. The leader device can include an interface configured to display a plurality of preview images, each preview image corresponding with respective virtual reality (VR) content. The leader device also include a selection device configured to select a preview image of the plurality of preview images and a leader application configured to control presentation of the respective VR content associated with the selected preview image. The system can further include a plurality of participant devices that are operationally coupled with the leader device. Each participant device of the plurality of participant devices can be configured to, responsive to the leader device, display at least one image included in the respective VR content corresponding with the selected preview image.

Abstract: In a general aspect, a system can include a leader device. The leader device can include an interface configured to display a plurality of preview images, each preview image corresponding with respective virtual reality (VR) content. The leader device also include a selection device configured to select a preview image of the plurality of preview images and a leader application configured to control presentation of the respective VR content associated with the selected preview image. The system can further include a plurality of participant devices that are operationally coupled with the leader device. Each participant device of the plurality of participant devices can be configured to, responsive to the leader device, display at least one image included in the respective VR content corresponding with the selected preview image.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, are described for identifying target terms, e.g., spam terms within a collection of documents. In one aspect, methods can include identifying spam terms by calculating a blacklist term frequency-inverse document frequency (BTF-IDF) score for multiple terms, and by selecting, as the spam terms, the terms that have scores above or below a threshold score. The multiple terms may be derived from documents that are associated with accounts that have been designated as spam accounts.