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Showing posts from December 30, 2018

GNU ld aborted for internal error when building LLVM

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0 When I tried to build LLVM 8 using gcc tool chains, some problems happened. First ld was killed, and as the build skipped this failure and continued, ld aborted itself with an internal error. Given a situation like this, what should I do to solve the problem and build LLVM successfully? It is known that LLVM demands a great deal of the host compiler. Below I try to provide as detailed configuration as possible: Host machine: Ubuntu 18.04.1 LTS bionic LLVM version: 8, obtained with command: git clone https://git.llvm.org/git/llvm.git/ ld version: 2.30 gcc version: 7.3.0 cmake version: 3.10.2 ninja version: 1.8.2 (I am using it in place of Unix Makefile) cmake command used: cmake -DCMAKE_INSTALL_PREFIX=$HOME -DLLVM_TARGETS_TO_BUILD="Mips;X86" -DCMAKE_BUILD_TYPE=RelWithDebInfo -DLLVM_OPT...

Group Theory (Sylow p-subgroups questions)

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0 Let $GL_nmathbb{F}_p$ be the group of invertible $n times n$ matrices with entries coming from $mathbb{F_p}={0, 1, ..., p-1}$ and with group operation multiplication of matrices. (We are writing $mathbb{F_p}$ for this object to not confuse it with $mathbb{Z_p}$ , the $group$ of integers modulo $p$ with the operation $+$ modulo $p$ ; $mathbb{F_p}$ is the $field$ of order $p$ , where $p$ is prime.) a) Show that $|GL_nmathbb{F_p}|=(p^n-1)(p^n-p)(p^n-p^2)...(p^n-p^{n-1})$ Hint: You need to use the invertible nature of the matrices when its columns are linearly independent. b) Show that $p cdot p^2 cdot ...cdot p^n$ is the largest power of $p$ dividing the order of $GL_nmathbb{F_p}$ c) Deduce that the matrices $A=(a_{ij})$ with $(a_{ij})=0$ when $i<j$ and $a_{ij}=1$ form a Sylow p-subgroup of $GL_...