A matroid can be defined in terms of bases. A matroid consists of a ground set as well as a set of bases which is a nonempty subset of the power set of the ground set.

Time passes sorrowly, rather than slowly; and my thoughts, without being amused, are employed.

Smal bodies, of Atoms, out of whose various combinations bigger molleculæ are made.

His turban, furled in many a graceful fold, / An emerald aigrette, with Haidée's hair in't, / Surmounted as its clasp […]