If a graph can be drawn on the torus so that every two independent edges cross an even number of times, then the graph can be embedded on the torus.

中文翻译：

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圆环的强 Hanani-Tutte

如果可以在圆环上绘制一个图，使得每两条独立边相交偶数次，那么该图就可以嵌入到圆环上。