You want a nice triple turnstile which matches in size and weight the usual Computer Modern \vdash and \vDash turnstiles?

Look no further. Here’s the trick, also linked for future reference on the LaTeX for Logicians symbols page.

You want a nice triple turnstile which matches in size and weight the usual Computer Modern \vdash and \vDash turnstiles?

Look no further. Here’s the trick, also linked for future reference on the LaTeX for Logicians symbols page.

Nicolas PottSpeaking about turnstiles, I wonder if you know who first invented the double turnstile as a symbol for semantic consequence and the model relation? The first appearance known to me is in fact Mendelsons Introduction to Mathematical Logic from 1964 (assuming that it was there already in the first edition, I have access only to the fourth). I tried to investigate this a bit, but found nothing on this matter so far.

Peter SmithNo — I don’t know the history of this!

Chris GrantThere’s a little bit of a discussion of the history of the double turnstile at the bottom of the webpage at: http://jeff560.tripod.com/set.html