Online panels have become a prominent way to collect survey data. They are used in many fields including market research (Comley, 2007; Göritz, 2010; Postoaca, 2006), social research (Tortora, 2008), psychological research (Göritz, 2007), election studies (Clarke, Sanders, Stewart, & Whiteley, 2008), and medical research (Couper, 2007). Panel-based online survey research has grown steadily over...

We discuss issues related to constructing an orthomodular structure from an object in a category. In particular, we consider axiomatics related to Baer *-semigroups, partial semigroups, and various constructions involving dagger categories, kernels, and biproducts.

We present a characterisation of { 1(q+1)+ 0, 1;n, q}-minihypers, q square, q = ph, p > 3 prime, h ≥ 2, q ≥ 1217, for 0+ 1 < q 7/12 2 − q1/4 2 . This improves a characterisation result of S. Ferret and L. Storme [6], involving more Baer subgeometries contained in the minihyper.

We introduce a dynamic and secondary-memory-based variant of the List of Clusters, which is shown to be competitive with the literature, especially on higher-dimensional spaces, where it outperforms the M-tree in searches and I/Os used for insertions. The basic principles of our design are applicable to other secondary-memory structures.

This paper presents characterizations of M-fuzzifying matroids bymeans of two kinds of fuzzy operators, called M-fuzzifying derived operatorsand M-fuzzifying difference derived operators.