In this paper we discuss approximation algorithms for the ELEMENT-DISJOINT STEINER TREE PACKING problem (Element-STP for short). For a graph G=(V,E) and a subset of nodes T⊆V, called terminal nodes, a Steiner tree is a connected, acyclic subgraph that contains all the terminal nodes in T. The goal of Element-STP is to find as many element-disjoint Steiner trees as possible. Element-STP is known to be APX-hard even for |T|=3 [1]. It is also known that Element-STP is NP-hard to approximate within a factor of Ω(log |V|) [3] and there is an O(log |V|)-approximation algorithm for Element-STP [2],[4]. In this paper, we provide a $lceil rac{|T|}{2} ceil$-approximation algorithm for Element-STP on graphs with |T| terminal nodes. Furthermore, we show that the approximation ratio of 3 for Element-STP on graphs with five terminal nodes can be improved to 2.

A component connection enables a component to use the functionality of other components directly, without generating adapters or other mechanisms at run-time. In conventional component connection models, the connection between components, particularly third-party components, is very costly for code reuse because the component source code must be modified if the types of requester-side and provider-side are different. This paper proposes a new component model, built upon an existing component architecture, which abandons a component service type and connects components based on a method type collection of the provider and requester components. Our model enables flexible connections owing to relaxed component matching, in which the system that implements our model automatically converts values of parameters, return values, and exceptions between required methods and provided ones within a well-defined range. As a result of experimental evaluations, it is found that our model is superior to conventional models in terms of the component-use cost and the capability of changing connections.