We show that, when the field strength H of the NS-NS B field does not vanish, the coordinates x and momenta p of open string end points satisfy a set of mixed commutation relations among themselves. Identifying x and p with the coordinates and derivatives of the D-brane world volume, we find a new type of noncommutative space which is very different from… (More)
An ω-language over a finite alphabet X is a set of infinite sequences of letters of X.) is the equality then L is called an I-disjunctive (P-disjunctive, O-disjunctive, respectively) ω-language. Properties concerning such ω-languages are explored and relations between these ω-languages are also studied.
We construct a modification of Churchill and Trotter's trifree objects in e-varieties of locally E-solid semigroups, which have the property, for e-varieties of locally inverse semigroups and for e-varieties of E-solid semigroups, of being isomorphic to the bifree objects.