The main purpose of this paper is to take apart the reducibility method in order to understand how its pieces fit together, and in particular, to recast the conditions on candidates of reducibility as sheaf conditions. there has been a feeling among experts on this subject that it should be possible to present the reducibility method using more semantic means, and that a deeper understanding wo...

x0. Introduction and Notation. Weak truth table reducibility (w-reducibility) was rst introduced by Friedberg and Rogers [FR59]. Intuitively, we say that a set A is w-reducible to a set B (written A w B) if there is a Turing reduction from A to B and a recursive function f such that, for any x, the value f(x) bounds the greatest number whose membership or nonmembership in B is used to determine...

the potential of carbon nanotubes (cnt) supported cobalt catalysts for fischer-tropsch (ft) reaction is shown. using the wet impregnation method cobalt on carbon nanotubes catalysts were prepared with cobalt loading varying from 15 to 45 wt. %. the catalysts are characterized by different methods including: bet physisorption, x-ray diffraction, hydrogen chemisorption, and temperature-programmed...

A graph is terminal ∆ − Y -reducible if, it can be reduced to a distinguished set of terminal vertices by a sequence of series-parallel reductions and ∆−Y -transformations. Terminal vertices (o terminals for short) cannot be deleted by reductions and transformations. Reducibility of terminal graphs is very difficult and in general not possible for graphs with more than three terminals (even pla...

The separability of a resistor-inductorcapacitor-mutual inductance (RLCM) network is defined in this paper. Some separability, reducibility and controllability (observability) criteria of RLCM networks over ( ) F z are derived. Two illustrative examples are given. Index Term—RLCM Networks, Separability, Reducibility, Controllability

Our main result is the equivalence of two notions of reducibility between structures. One is a syntactical notion which is an effective version of interpretability as in model theory, and the other one is a computational notion which is a strengthening of the wellknown Medvedev reducibility. We extend our result to effective biinterpretability and also to effective reductions between classes of...