Tag Archives: toposes

Posted on February 18, 2012 by isomorphismes

The definition of toposes has surprisingly powerful consequences. (For example, toposes have all finite colimits.) Probably the best analogy elsewhere in which a couple of mild-sounding hypotheses pick out a very narrow and interesting class of examples is the way … Continue reading →

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Posted on January 16, 2012 by isomorphismes

The ontological commitment of a sentence is whatever must be among the values of bound variables for the sentence to come out as true. Willard van Orman Quine I bring up this quotation not to agree or disagree with Quine, … Continue reading →

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Posted on December 19, 2011 by isomorphismes

http://www.cs.ox.ac.uk/quantum/talksarchive/clap1/clap1-chrisisham.avi Is there really such a thing as a point? Well, not really…. Ask any of our undergraduates, why the real numbers? Can you say there’s something √π centimetres away from here?—Well, not really, it’s an approximation….—An approximation to what? “We’re not … Continue reading →

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Posted on May 15, 2011 by isomorphismes

“Have you ever done acid, kid? This book is like Acid.” —John L. Rhodes, speaking of the book Topos Theory by Peter Johnstone (Source: http://www.amazon.com/gp/product/0521337798?ie=UTF8&tag=hiremebecauim-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0521337798)

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