Command `\lneq' already defined. ...mbol{\lneq} {\mathrel}{AMSb}{"0C}

[political science]

Here is a link to thesis
https://github.com/kiotie32/thesissokoeradoera
I am compiling it on Miktex 2.9
I get error in amssymb.sty
line 183 Command `\lneq' already defined. ...mbol{\lneq}
{\mathrel}{AMSb}{"0C}
line 441 Command \proof already defined. }
line 385 File ended while scanning use of \next. \input{texfiles/chapter4}
Emergency stop.

I am not an expert of latex just a basic read write syntax I read and wrote
and wrote something.Just a basic understanding I have.
I am not able to understand above errors why are they coming.
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