A Series of Quasi-Multiple \(BIB\) Designs from Hadamard Matrices

A method of construction of quasi-multiple balanced incomplete block \((BIB)\) designs from certain group divisible designs is described. This leads to a series of quasi-multiple designs of symmetric BIB designs and new non-isomorphic solutions of designs listed as unknown in the tables of Mathon and Rosa \([{3,4}]\). In the process a series of semi-regular group divisible designs is also obtained.