In this paper, we propose a new class of parallel branch-and-bound (B&B) schemes. The main idea of the scheme is to focus on the functional parallelism instead of conventional data parallelism, and to support such a heterogeneous and irregular parallelism by using a collection of autonomous agents distributed over the network. After examining several design issues toward the implementation of a prototype of the distributed B&B system, we illustrate the result of our preliminary experiments conducted to estimate the performance of the proposed scheme. The result shows that it could cause a significant performance improvement if each agent autonomously changes its function type according to the change of the underlying environment.