  Individuals have opinions but can change them under the influence of others.
The recent models of Sznajd (missionaries), of Deffuant et al. (negotiators),
and of Krause and Hegselmann (opportunists) are reviewed here, while the voter
and Ising models, Galam's majority rule and the Axelrod multicultural model
were dealt with by other lecturers at this 8th Granada Seminar.
