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What is the inverse of a circle?

mattferraro.dev

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Re: What is the inverse of a circle?

#13

I did some wacky inside-out pics of planets years ago, inspired by the inside-out Mandelbrot set looking like a leaf/teardrop. https://www.adamponting.com/inside-out/ Related: Not Knot , 1991 Thurston-ish short film about knots and knot complements - "the space where the knot isn't". https://www.youtube.com/watch?v=zd_HGjH7QZo https://en.wikipedia.org/wiki/Not_Knot https://en.wikipedia.org/wiki/Knot_complement

That knot of Saturn looks like art to me. Anyway hats off for being to play with geometry like that.

Re: What is the inverse of a circle?

#17

The answer is “it depends on how you defined the operation that acts on the circle”

This is it. Inverse is a property of functions or other relational operators, not "static" individual objects. You need a direction in order to invert it.

The multiplicative inverse, or reciprocal, or the inverse of a number, is a function acting on a number, 1/x, or x^-1.

Re: What is the inverse of a circle?

#18
post #17

Earlier quoted context omitted.

This is it. Inverse is a property of functions or other relational operators, not "static" individual objects. You need a direction in order to invert it.

The multiplicative inverse, or reciprocal, or the inverse of a number, is a function acting on a number, 1/x, or x^-1.

Isn't this a case of multiplication being such a "well-known" function that the "inverse" defaults to "multiplicative inverse"?

Re: What is the inverse of a circle?

#19
post #17

Earlier quoted context omitted.

This is it. Inverse is a property of functions or other relational operators, not "static" individual objects. You need a direction in order to invert it.

The multiplicative inverse, or reciprocal, or the inverse of a number, is a function acting on a number, 1/x, or x^-1.

The multiplicative inverse of a number n can be seen as the inverse of the function that multiplies its input by n. That is, the inverse of multiplication by n is multiplication by 1/n.

Similarly, the additive inverse of a number m is the inverse of the function that adds m to its input.

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