16 lines
326 B
Text
16 lines
326 B
Text
import algebra.group
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open path_algebra
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variable {A : Type}
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variable [s : add_comm_group A]
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include s
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theorem add_minus_cancel_left1 (a b c : A) : (c + a) - (c + b) = a - b :=
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begin
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rotate_left 1,
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apply sorry
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end
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theorem add_minus_cancel_left2 (a b c : A) : (c + a) - (c + b) = a - b :=
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by rotate_left 1;
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apply sorry
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