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University of Florence


2d
answered How to graph functions without a calculator?
2d
revised Verify my proof: If $X$ is infinite, then there exists $f: \mathbb{N} \rightarrow X$ such that $f$ is injective.
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2d
comment Verify my proof: If $X$ is infinite, then there exists $f: \mathbb{N} \rightarrow X$ such that $f$ is injective.
@Guilherm: I cannot understand your proof. Seems you are saying: take the function $f$ such that the maximal set where $f$ is injective, is maximal. It's not clear at all how you can define such things. Take $f(n)=\lfloor n/2\rfloor$ and explain what is $k$ for such a function. Also the notation $a \neq b \neq c$ is bad, don't use it.
Aug
26
answered Verify my proof: If $X$ is infinite, then there exists $f: \mathbb{N} \rightarrow X$ such that $f$ is injective.
Aug
26
answered Is the dot product valid for coordinate vectors of infinite length?
Aug
26
revised Can I conjugate a complex number: $\sqrt{a+ib}$?
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Aug
26
answered Can I conjugate a complex number: $\sqrt{a+ib}$?
Aug
26
revised Can I conjugate a complex number: $\sqrt{a+ib}$?
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Aug
26
answered Computing $\sum_{i=0}^{\infty}\frac{i}{2^{i+1}}$
Aug
26
revised Min and max of a product.
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Aug
26
revised Min and max of a product.
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Aug
26
answered Min and max of a product.
Aug
26
answered Range of a trigonometric function
Aug
21
comment Summation of cosines
Take $n=2$ and $j=1$ to see it's false
Aug
21
revised Summation of cosines
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Aug
18
revised Method for computing limit of a sin function as x tends to zero
sign
Aug
17
answered Show that for $(X,d)$ a metric space, $U= \{x \in X: d(x, C) \leq d(p, C)\}$ is a closed set
Aug
10
answered Can I say that an implicit function of space (3D) always has 3 unknowns?
Aug
7
comment Uniform continuity of a subset of $R$
I'm saying that you don't need the concept of limit to define continuity nor uniform continuity. As a matter of fact every function defined on $\{1,2,3\}$ is uniformly continuous.
Aug
7
revised Uniform continuity of a subset of $R$
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