The meaning of various equality symbols Ask Question Asked 10 years, 11 months ago Modified 9 years, 11 months ago This page is from Measure and category by John C. Oxtoby page 20. What is the meaning of this symbol?

Context Explanation

I added a red line under it. There is no definition of this symbol in this book, so I couldn't In summary: The interplay of meaning and axiomatic machine mathematics, captured by the difference between $\models$ and $\vdash$, is a subtle and interesting thing.