Wednesday, January 12, 2011

Proof by silence

What is a proof by silence? The speaker makes a statement. They say: "Proof". They then stop talking, leaving silence hanging for a few moments. When they see several people nodding in the audience, they say: "End of proof", and move on to the rest of the talk or lecture.

Why? When a statement is straightforward for the audience, it may be easier for them to figure out by themselves why the statement holds rather than listen to an explanation.

Example: For an audience of graduate students and researchers, the statement: "Every graph with maximum degree d is can be colored with d+1 colors" is straightforward.


  1. Funny, I read your statement on graph colorability, instinctively thought about the issue (I seldom work on graph algorithms, so it's not something I would say immediately), and ended up nodding after a few seconds. This is a very effective technique indeed.


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