There is a comeager set C contained in the set of 1-generic reals and a first order structure M such that for any real number X, there is an element of C which is recursive in X if and only if there is a presentation of M which is recursive in X.

The degree structure of functions induced by a polynomial-time reducibility first introduced in G. Miller's work on the complexity of prime factorization is investigated. Several basic results are established including the facts that the degrees restricted to the sets do not form an upper semilattice and there is a minimal degree, as well as density for the low degrees, a weak form of the exact pair theorem, the existence of minimal pairs and the decidability of the Π2 theory of the (...) low degrees. (shrink)

科学が自然を破壊した今、人間は人工的に反人工的な自然を保持するべく努力しなければなりません。科学技術は、この逆説に耐え抜かねばならないのでしょう。.

For a prime k, the embeddability of finite lattices are discussed for various kind of the MODkP degrees of recursive sets. In particular, all finite lattices are embeddable into the MODkP Turing degrees, whereas the non distributive lattice M3 is embeddable into the MOD2P many-one degrees but N5 is not.

The structure of the p-s-degrees of recursive functions is shown to be inhomogeneous. There are two p-s-degrees a and b above 0 such that [0, a] is distributive and [0, b] is nondistributive. Moreover, we will investigate how the number of values of each function reflects on its degree.