Text: In addition to the quarterly meetings, informal meetings and teleconferences are held among members on an ad hoc basis to discuss issues as they arise, such as assisting entities under attack.
Entailment: Informal meetings and teleconferences were held on an as need be basis when important issues arise, such as assisting entities under attack, as well as the scheduled quarterly meetings.
Contradiction: The company only allowed its employees to discuss important matters during the scheduled quarterly meetings.