An exact whole power with a huge exponent hangs evaluation: 2^(10^9), 2^(3^20)
维护者通常 1 天内回复
还没有人认领这个 Issue。
评估
- 难度
- 5/5
- 预计耗时
- 一周以上
- 新手友好度
- 32/100
- Issue 类型
- 缺陷
- 描述清晰度
- 需要澄清
- 活跃度
- 活跃
- 技术栈
- csharp
- 领域
- performance
调研方向
Start by reproducing the two expressions through ToEntity().Evaled and trace the Number.Pow/BinaryIntPow path described in the issue. Review the quantifier witness-search path and related issue #1338, then establish the chosen behavior for oversized exact powers and confirm that witness searches remain bounded without silently losing exactness.
由索引模型根据 Issue 内容生成。
描述
"2^(10^9)".ToEntity().Evaled and "2^(3^20)".ToEntity().Evaled do not return (killed at 60 s each; 2^(3^12) returns in 1 s). The result of the first is a 10⁹-bit integer (125 MB) and of the second a 3.5·10⁹-bit one; Number.Pow's BinaryIntPow builds them by squaring in EInteger, and the last squarings are Toom-4 multiplications of numbers hundreds of megabytes long. Measured on 8fcfaf42 (a branch of 345914f6); the code path is unchanged since long before.
Found through a quantifier: forall n in ZZ* : 3^(n + 1) divides 2^(3^n) + 1 (Sullivan and Mackey's Prob 5.7.13) hangs because a witness search evaluates the body at n = 20 or so, where 2^(3^n) is the second number above. Any consumer that evaluates a tower at a large argument hits the same.
What the answer should be is the decision to make, and it belongs with #1338's numerics: an exact power whose result would exceed some size — say 2²⁴ bits, which is 2 MB and a fraction of a second — is either (a) left as written (2^(10^9) evaluates to itself, the way an unsolved statement stays a statement), or (b) refused with an exception naming the limit, or (c) evaluated approximately as Real at the working precision, which is what a decimal calculator does and loses exactness silently. (a) is the honest one under not answering is legitimate; answering wrongly is not, and it composes: a witness search that gets an unevaluated power back moves on. Until then, a quantifier's witness search should skip a sample it cannot evaluate in bounded time, which is the narrower fix I would take first.
Part of #1409.
🤖 Generated with Claude Code
- 主要语言
- C#
- 星标
- 831
- 派生
- 79
- 平均合并
- 2 小时 17 分钟
- 30 天内合并 PR
- 443
环境准备
- 没有 Dockerfile 或 Docker Compose 文件
- 没有 Pull Request 模板
- 阅读贡献指南
从这里开始
- 先读完整个 Issue，再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库，在一个分支上完成修改。
- 提交 Pull Request，并在描述里引用这个 Issue 编号。
ASC-Community/AngouriMath 的其他 Issue
-
难度 5/5 一周以上 新手友好度 12/100
ASC-Community/AngouriMath#1885 ·
维护者通常 1 天内回复
-
难度 4/5 3-5 天 新手友好度 35/100
ASC-Community/AngouriMath#1883 ·
维护者通常 1 天内回复
-
难度 5/5 一周以上 新手友好度 30/100
ASC-Community/AngouriMath#1807 · 1 条评论 ·
维护者通常 1 天内回复
-
难度 5/5 一周以上 新手友好度 25/100
ASC-Community/AngouriMath#1692 ·
维护者通常 1 天内回复
-
难度 5/5 一周以上 新手友好度 30/100
ASC-Community/AngouriMath#1690 ·
维护者通常 1 天内回复
查看 ASC-Community/AngouriMath 的全部 Issue
相似的 Issue
-
documentation good first issue
难度 2/5 1-3 小时 新手友好度 65/100
维护者通常 1 天内回复
-
[Bug]: Edit Bar buttons are not localized可能已有人在做 @idumlupinar 今天认领。 未关闭Status: New
难度 2/5 1-3 小时 新手友好度 70/100
dnnsoftware/Dnn.Platform#7565 ·
维护者通常 1 天内回复
-
enhancement
难度 2/5 半天 新手友好度 72/100
-
bug ui-only
难度 2/5 1-3 小时 新手友好度 72/100
维护者通常 1 天内回复
-
bug
难度 2/5 1-3 小时 新手友好度 78/100
ClickHouse/clickhouse-cs#689 ·
维护者通常 2 天内回复