Assume that \({{\mathfrak {H}}}\) and \({{\mathfrak {K}}}\) are two real or complex Hilbert spaces, A a linear relation from \({{\mathfrak {H}}}\) to \({{\mathfrak {K}}}\) and B a linear relation from \({{\mathfrak {K}}}\) to \({{\mathfrak {H}}}\), respectively. Necessary and sufficient conditions for B to be equal to the adjoint of A are provided. New characterizations for closed, skew–adjoint and selfadjoint linear relations are obtained.

中文翻译：

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彼此相邻的线性关系。涅米宁类型标准

假设\（{{\ mathfrak {H}}} \）和\（{{\ mathfrak {K}}} \）是两个实数或复数Hilbert空间，甲从线性关系\（{{\ mathfrak {H }}}\)到\({{\mathfrak {K}}}\)和B从\({{\mathfrak {K}}}\)到\({{\mathfrak {H}}}的线性关系\)，分别。提供了B等于A的伴随条件的充分必要条件。获得了封闭、倾斜-伴随和自伴随线性关系的新特征。