John Douma

 26 Proof: 1007 can not be written as the sum of two primes. 16 Counting binary operations on a set with $n$ elements 12 What is sum of all positive odd integers less than $1000$? 11 How do we know the ratio between circumference and diameter is the same for all circles? 10 How do I find a point a given distance from another point along a line?

Reputation (5,820)

 +20 $X,Y$ not homeomorphic if $X\backslash x$ is disconnected for all $x\in X$ but $Y\backslash y$ is connected for some $y\in Y$ +10 Why did the natural constant e had to be 2.718.. +25 Monomorphism and identity function +15 Functions of vectors and vectors of functions

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Tags (184)

 43 linear-algebra × 30 31 calculus × 30 41 elementary-set-theory × 13 28 proof-verification × 5 39 abstract-algebra × 11 28 prime-numbers × 3 35 geometry × 18 27 general-topology × 13 32 real-analysis × 23 26 discrete-mathematics × 13

Accounts (6)

 Mathematics 5,820 rep 21520 MathOverflow 101 rep Stack Overflow 101 rep 2 Music: Practice & Theory 101 rep Physics 101 rep