On formal power series defined by infinite linear systems

Linear Differential Systems with Infinite Power Series Coefficients (Invited Talk)

On Formal Power Series Generated by Lindenmayer Systems

To study power series generated by Lindenmayer systems we de ne L algebraic systems and series over arbitrary commutative semirings. We establish closure and xed point properties of L algebraic series. We show how the framework of L algebraic series can be used to de ne D0L, 0L, E0L, DT0L, T0L and ET0L power series. We generalize for power series the classical result stating that D0L languages ...

On sequences defined by D0L power series

We study D0L power series over commutative semirings. We show that a sequence (cn)n 0 of nonzero elements of a eld A is the coe cient sequence of a D0L power series if and only if there exist a positive integer k and integers i for 1 i k such that cn+k = c 1 n+k 1c 2 n+k 2 : : : c k n for all n 0. As a consequence we solve the equivalence problem of D0L power series over computable elds. TUCS R...

On skew formal power series

We investigate the theory of skew (formal) power series introduced by Droste, Kuske [4, 5], if the basic semiring is a Conway semiring. This yields Kleene Theorems for skew power series, whose supports contain finite and infinite words. We then develop a theory of convergence in semirings of skew power series based on the discrete convergence. As an application this yields a Kleene Theorem prov...

ALGEBRAIC INDEPENENCE OF CERTAIN FORMAL POWER SERIES (II)

We shall extend the results of [5] and prove that if f = Z o a x ? Z [[X]] is algebraic over Q (x), where a = 1, ƒ 1 and if ? , ? ,..., ? are p-adic integers, then 1 ? , ? ,..., ? are linkarly independent over Q if and only if (1+x) ,(1+x) ,…,(1+x) are algebraically independent over Q (x) if and only if f , f ,.., f are algebraically independent over Q (x)