TY - JOUR AU - Beker, H. AU - Mitchell, Ch. AU - Piper, F. TI - Tactical decompositions of designs. JO - Aequationes mathematicae PY - 1982 VL - 25 SP - 123 EP - 152 KW - t-design; incidence matrix; residual design; quasi-residual design; point-tactical design; block-tactical design; divisible design; Hasse- Minkowski invariant UR - http://eudml.org/doc/136960 ER -