Function learn_shared 

pub fn learn_shared(
    ballots: &[(String, String)],
    outcome: &str,
    rows: &[Trust],
    beta: f64,
    about: &[String],
    share: f64,
) -> Result<Vec<Trust>>

learn_about with a fixed share of recovery: after the Hedge step every row moves toward one by share of the gap, so a voter refuted long ago is not held down forever and the best voter can change (Herbster and Warmuth, doi:10.1023/A:1007424614876). Zero is plain Hedge; the seat’s default.