The straight line programs and computa ti on trees are two better models of computation for the research of algebraic prob lems over a ring(or a field),especially the Lower bounds of the complexity of th e complexity.
直线程序和计算树模型是两个研究环（或域）上代数问题复杂性的较好的计算模型，特别是对问题复杂性下界的研究是很方便的。
