A search for CP violating effects in the mixing of neutral B mesons is perf
ormed using a sample of 4.1 million hadronic Z decays collected with the AL
EPH detector from 1991 to 1995. By studying time-dependent asymmetries in f
lavour-tagged samples of semileptonic and fully inclusive b-hadron decays,
two measurements of the semileptonic asymmetry acp are extracted. No eviden
ce for CP violation is observed, and the combined value a(CP) = -0.013 +/-
0.026 is obtained.