In this paper we deal with a subclass of chordal graphs, which are simultaneously strictly chordal and interval, the strictly interval graphs. We present a new characterization of the class that leads to a simple linear recognition algorithm. Next we introduce a new subclass of strictly interval graphs, the $SI$-core graphs, that are non-split and non-cograph graphs and show that several elements of the new class are Laplacian integral

翻译：本文研究弦图的一个子类——严格区间图，这类图同时具有严格弦图和区间图的性质。我们给出了该图类的一个新刻画，并由此提出了一个简单的线性识别算法。进一步，我们引入了严格区间图的一个新子类——$SI$-核图，这类图是非分裂图且非余图，并证明了该新子类中的若干元素是拉普拉斯整图。