I Graph Theory: I understanding the corollaries

AI Thread Summary
The discussion revolves around understanding the intersection number in graph theory, specifically when it is less than the number of edges. A clarification is sought regarding subsets in relation to vertices and their incident edges, questioning whether a subset Si includes both a vertex and its connecting edges. Participants are encouraged to provide insights on these concepts. The conversation emphasizes the need for clear definitions and examples to enhance comprehension of these graph theory principles. Overall, the thread aims to clarify foundational aspects of graph theory related to intersection numbers and subset definitions.
Terrell
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please check the attached photo
 

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Terrell said:
please check the attached photo

What is your question?
 
Math_QED said:
What is your question?
when is the intersection number less than the number of edges?

also a clarification i need, in Si s.t. Si is subset of S, does it contain v_i together with edges incident to it? so meaning it is a set containing a vertex and edges?
 
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