I review the development of numerical evolution codes for general relativity based upon the characteristic initial-value problem. Progress in characteristic evolution is traced from the early stage of 1D feasibility studies to 2D-axisymmetric codes that accurately simulate the oscillations and gravitational collapse of relativistic stars and to current 3D codes that provide pieces of a binary black-hole spacetime. Cauchy codes have now been successful at simulating all aspects of the binary black-hole problem inside an artificially constructed outer boundary. A prime application of characteristic evolution is to extend such simulations to null infinity where the waveform from the binary inspiral and merger can be unambiguously computed. This has now been accomplished by Cauchy-characteristic extraction, where data for the characteristic evolution is supplied by Cauchy data on an extraction worldtube inside the artificial outer boundary. The ultimate application of characteristic evolution is to eliminate the role of this outer boundary by constructing a global solution via Cauchy-characteristic matching. Progress in this direction is discussed.

中文翻译：

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特征演变和匹配。

我回顾了基于特征初值问题的广义相对论数字演化代码的发展。从1D可行性研究的早期阶段开始，就可以追踪特征演化的进展，其中包括可以精确模拟相对论恒星的振荡和重力塌陷的2D轴对称代码，以及可以提供双黑洞时空碎片的当前3D代码。柯西代码现在已经成功地模拟了人工构造的外部边界内的二进制黑洞问题的所有方面。特征演化的主要应用是将这种模拟扩展到零无穷大，在该无穷大中可以明确地计算来自二进制启发和合并的波形。现在已经通过柯西特征提取实现了这一点，其中，由柯西（Cauchy）数据在人造外边界内的提取世界管上提供特征进化的数据。特征演化的最终应用是通过柯西特征匹配构造全局解决方案，从而消除该外部边界的作用。讨论了朝这个方向的进展。