How to prove a numerical identity?
$begingroup$
Let be a function power function
f[s_, r_] := Piecewise[{{s^r, s >= 0}, {0, True}}];
And its convolution
Conv[s_, r_] := Sum[f[k, r]*f[s - k, r], {k, -Infinity, +Infinity}];
Proposition 1. Let be a real coefficients $A_{m,j}$ defined as follows
A[n_, k_] := 0
A[n_, k_] := (2 k + 1)*Binomial[2 k, k]*
Sum[A[n, j]*Binomial[j, 2 k + 1]*(-1)^(j - 1)/(j - k)*
BernoulliB[2 j - 2 k], {j, 2 k + 1, n}] /; 2 k + 1 <= n
A[n_, k_] := (2 n + 1)*Binomial[2 n, n] /; k == n;
Then for every $n,m in mathbb{N}$ there is an identity,
$$n^{2m+1}+1=sum_{r=0}^{m}A_{m,r}mathrm{Conv}_r[n], n>0 tag1$$
where $mathrm{Conv}_r[n]=(f_{r}*f_{r})[n]=sum_{t}f_r(t)f_r(n-t)$.
Expression $(1)$ is implemented in Mathematica as folows
MainIdentity[m_, n_] := Sum[A[m, r]*Conv[n, r], {r, 0, m}];
And numerically it is equal to $n^{2m+1}$ for any naturals $m,n$, for example the tabular arrangement
n = 3; Table[MainIdentity[m, n], {m, 0, 11}]
gives
{4, 28, 244, 2188, 19684, 177148, 1594324, 14348908, 129140164}
Which is set of $3^{2m+1}+1, m=0,1,2,3.. $. But when the condition is checked by mathematica with ==
operator,
FullSimplify[MainIdentity[m, n], Assumptions -> n > 0] ==
First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
it gives False
.
Question 1: Is there any other methods of comparison, so we can verify the formula $(1)$ ?
Question 2: Execution time of the Mathematica implementation of $(1)$ is very slow, can we optimaze the solution in order to decrese exec. time ?
expression-test convolution testing-and-verification
$endgroup$
|
show 2 more comments
$begingroup$
Let be a function power function
f[s_, r_] := Piecewise[{{s^r, s >= 0}, {0, True}}];
And its convolution
Conv[s_, r_] := Sum[f[k, r]*f[s - k, r], {k, -Infinity, +Infinity}];
Proposition 1. Let be a real coefficients $A_{m,j}$ defined as follows
A[n_, k_] := 0
A[n_, k_] := (2 k + 1)*Binomial[2 k, k]*
Sum[A[n, j]*Binomial[j, 2 k + 1]*(-1)^(j - 1)/(j - k)*
BernoulliB[2 j - 2 k], {j, 2 k + 1, n}] /; 2 k + 1 <= n
A[n_, k_] := (2 n + 1)*Binomial[2 n, n] /; k == n;
Then for every $n,m in mathbb{N}$ there is an identity,
$$n^{2m+1}+1=sum_{r=0}^{m}A_{m,r}mathrm{Conv}_r[n], n>0 tag1$$
where $mathrm{Conv}_r[n]=(f_{r}*f_{r})[n]=sum_{t}f_r(t)f_r(n-t)$.
Expression $(1)$ is implemented in Mathematica as folows
MainIdentity[m_, n_] := Sum[A[m, r]*Conv[n, r], {r, 0, m}];
And numerically it is equal to $n^{2m+1}$ for any naturals $m,n$, for example the tabular arrangement
n = 3; Table[MainIdentity[m, n], {m, 0, 11}]
gives
{4, 28, 244, 2188, 19684, 177148, 1594324, 14348908, 129140164}
Which is set of $3^{2m+1}+1, m=0,1,2,3.. $. But when the condition is checked by mathematica with ==
operator,
FullSimplify[MainIdentity[m, n], Assumptions -> n > 0] ==
First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
it gives False
.
Question 1: Is there any other methods of comparison, so we can verify the formula $(1)$ ?
Question 2: Execution time of the Mathematica implementation of $(1)$ is very slow, can we optimaze the solution in order to decrese exec. time ?
expression-test convolution testing-and-verification
$endgroup$
$begingroup$
An important question: What is0^0
for you?
$endgroup$
– Henrik Schumacher
16 hours ago
1
$begingroup$
For Q1 you can usePossibleZeroQ
to check if the difference between the expressions is zero: reference.wolfram.com/language/ref/PossibleZeroQ.html
$endgroup$
– Roman
16 hours ago
$begingroup$
What's the purpose ofFirst
in[...] == First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
. Not that it returns1
!
$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
@HenrikSchumacher I think now it is common agreement that $0^0 = 1$, I prefer to reffer it to Knuth's Concrete mathematics. ConcerningFirst
I dont really know Mathematica well, so I just entered my function into the pattern I found in one of my previous questions here
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
Whenn
ork
is not numerical, the conditions2 k + 1 <= n
andk == n
are not evaluated andA[n,k]
evaluates to the first, unconditioned definition ofA
which is0
. So in total, your definition ofA
is not appropriate for symbolic evaluation.
$endgroup$
– Henrik Schumacher
15 hours ago
|
show 2 more comments
$begingroup$
Let be a function power function
f[s_, r_] := Piecewise[{{s^r, s >= 0}, {0, True}}];
And its convolution
Conv[s_, r_] := Sum[f[k, r]*f[s - k, r], {k, -Infinity, +Infinity}];
Proposition 1. Let be a real coefficients $A_{m,j}$ defined as follows
A[n_, k_] := 0
A[n_, k_] := (2 k + 1)*Binomial[2 k, k]*
Sum[A[n, j]*Binomial[j, 2 k + 1]*(-1)^(j - 1)/(j - k)*
BernoulliB[2 j - 2 k], {j, 2 k + 1, n}] /; 2 k + 1 <= n
A[n_, k_] := (2 n + 1)*Binomial[2 n, n] /; k == n;
Then for every $n,m in mathbb{N}$ there is an identity,
$$n^{2m+1}+1=sum_{r=0}^{m}A_{m,r}mathrm{Conv}_r[n], n>0 tag1$$
where $mathrm{Conv}_r[n]=(f_{r}*f_{r})[n]=sum_{t}f_r(t)f_r(n-t)$.
Expression $(1)$ is implemented in Mathematica as folows
MainIdentity[m_, n_] := Sum[A[m, r]*Conv[n, r], {r, 0, m}];
And numerically it is equal to $n^{2m+1}$ for any naturals $m,n$, for example the tabular arrangement
n = 3; Table[MainIdentity[m, n], {m, 0, 11}]
gives
{4, 28, 244, 2188, 19684, 177148, 1594324, 14348908, 129140164}
Which is set of $3^{2m+1}+1, m=0,1,2,3.. $. But when the condition is checked by mathematica with ==
operator,
FullSimplify[MainIdentity[m, n], Assumptions -> n > 0] ==
First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
it gives False
.
Question 1: Is there any other methods of comparison, so we can verify the formula $(1)$ ?
Question 2: Execution time of the Mathematica implementation of $(1)$ is very slow, can we optimaze the solution in order to decrese exec. time ?
expression-test convolution testing-and-verification
$endgroup$
Let be a function power function
f[s_, r_] := Piecewise[{{s^r, s >= 0}, {0, True}}];
And its convolution
Conv[s_, r_] := Sum[f[k, r]*f[s - k, r], {k, -Infinity, +Infinity}];
Proposition 1. Let be a real coefficients $A_{m,j}$ defined as follows
A[n_, k_] := 0
A[n_, k_] := (2 k + 1)*Binomial[2 k, k]*
Sum[A[n, j]*Binomial[j, 2 k + 1]*(-1)^(j - 1)/(j - k)*
BernoulliB[2 j - 2 k], {j, 2 k + 1, n}] /; 2 k + 1 <= n
A[n_, k_] := (2 n + 1)*Binomial[2 n, n] /; k == n;
Then for every $n,m in mathbb{N}$ there is an identity,
$$n^{2m+1}+1=sum_{r=0}^{m}A_{m,r}mathrm{Conv}_r[n], n>0 tag1$$
where $mathrm{Conv}_r[n]=(f_{r}*f_{r})[n]=sum_{t}f_r(t)f_r(n-t)$.
Expression $(1)$ is implemented in Mathematica as folows
MainIdentity[m_, n_] := Sum[A[m, r]*Conv[n, r], {r, 0, m}];
And numerically it is equal to $n^{2m+1}$ for any naturals $m,n$, for example the tabular arrangement
n = 3; Table[MainIdentity[m, n], {m, 0, 11}]
gives
{4, 28, 244, 2188, 19684, 177148, 1594324, 14348908, 129140164}
Which is set of $3^{2m+1}+1, m=0,1,2,3.. $. But when the condition is checked by mathematica with ==
operator,
FullSimplify[MainIdentity[m, n], Assumptions -> n > 0] ==
First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
it gives False
.
Question 1: Is there any other methods of comparison, so we can verify the formula $(1)$ ?
Question 2: Execution time of the Mathematica implementation of $(1)$ is very slow, can we optimaze the solution in order to decrese exec. time ?
expression-test convolution testing-and-verification
expression-test convolution testing-and-verification
edited 15 hours ago
Petro Kolosov
asked 16 hours ago
Petro KolosovPetro Kolosov
367
367
$begingroup$
An important question: What is0^0
for you?
$endgroup$
– Henrik Schumacher
16 hours ago
1
$begingroup$
For Q1 you can usePossibleZeroQ
to check if the difference between the expressions is zero: reference.wolfram.com/language/ref/PossibleZeroQ.html
$endgroup$
– Roman
16 hours ago
$begingroup$
What's the purpose ofFirst
in[...] == First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
. Not that it returns1
!
$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
@HenrikSchumacher I think now it is common agreement that $0^0 = 1$, I prefer to reffer it to Knuth's Concrete mathematics. ConcerningFirst
I dont really know Mathematica well, so I just entered my function into the pattern I found in one of my previous questions here
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
Whenn
ork
is not numerical, the conditions2 k + 1 <= n
andk == n
are not evaluated andA[n,k]
evaluates to the first, unconditioned definition ofA
which is0
. So in total, your definition ofA
is not appropriate for symbolic evaluation.
$endgroup$
– Henrik Schumacher
15 hours ago
|
show 2 more comments
$begingroup$
An important question: What is0^0
for you?
$endgroup$
– Henrik Schumacher
16 hours ago
1
$begingroup$
For Q1 you can usePossibleZeroQ
to check if the difference between the expressions is zero: reference.wolfram.com/language/ref/PossibleZeroQ.html
$endgroup$
– Roman
16 hours ago
$begingroup$
What's the purpose ofFirst
in[...] == First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
. Not that it returns1
!
$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
@HenrikSchumacher I think now it is common agreement that $0^0 = 1$, I prefer to reffer it to Knuth's Concrete mathematics. ConcerningFirst
I dont really know Mathematica well, so I just entered my function into the pattern I found in one of my previous questions here
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
Whenn
ork
is not numerical, the conditions2 k + 1 <= n
andk == n
are not evaluated andA[n,k]
evaluates to the first, unconditioned definition ofA
which is0
. So in total, your definition ofA
is not appropriate for symbolic evaluation.
$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
An important question: What is
0^0
for you?$endgroup$
– Henrik Schumacher
16 hours ago
$begingroup$
An important question: What is
0^0
for you?$endgroup$
– Henrik Schumacher
16 hours ago
1
1
$begingroup$
For Q1 you can use
PossibleZeroQ
to check if the difference between the expressions is zero: reference.wolfram.com/language/ref/PossibleZeroQ.html$endgroup$
– Roman
16 hours ago
$begingroup$
For Q1 you can use
PossibleZeroQ
to check if the difference between the expressions is zero: reference.wolfram.com/language/ref/PossibleZeroQ.html$endgroup$
– Roman
16 hours ago
$begingroup$
What's the purpose of
First
in [...] == First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
. Not that it returns 1
!$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
What's the purpose of
First
in [...] == First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
. Not that it returns 1
!$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
@HenrikSchumacher I think now it is common agreement that $0^0 = 1$, I prefer to reffer it to Knuth's Concrete mathematics. Concerning
First
I dont really know Mathematica well, so I just entered my function into the pattern I found in one of my previous questions here$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
@HenrikSchumacher I think now it is common agreement that $0^0 = 1$, I prefer to reffer it to Knuth's Concrete mathematics. Concerning
First
I dont really know Mathematica well, so I just entered my function into the pattern I found in one of my previous questions here$endgroup$
– Petro Kolosov
15 hours ago
1
1
$begingroup$
When
n
or k
is not numerical, the conditions 2 k + 1 <= n
and k == n
are not evaluated and A[n,k]
evaluates to the first, unconditioned definition of A
which is 0
. So in total, your definition of A
is not appropriate for symbolic evaluation.$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
When
n
or k
is not numerical, the conditions 2 k + 1 <= n
and k == n
are not evaluated and A[n,k]
evaluates to the first, unconditioned definition of A
which is 0
. So in total, your definition of A
is not appropriate for symbolic evaluation.$endgroup$
– Henrik Schumacher
15 hours ago
|
show 2 more comments
1 Answer
1
active
oldest
votes
$begingroup$
Towards Question 2: Make it a finite sum in Conv
. Indeed, there are only finitely many nonzero summands. Or better use Dot
.
f2[s_, r_] := s^r UnitStep[s];
Conv2[s_, r_] := #.Reverse[#] &[f2[Range[0, s], r]]
m = 10;
aa = Outer[Conv, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
bb = Outer[Conv2, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
aa == bb
11.0072
0.001253
True
$endgroup$
$begingroup$
As I see you use==
on the values of Timings or ? Still, the main aim is to show thatMainIdentity[m_, n_] == n^(2m+1)+1
.
$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
I applied==
to the outputs ofConv
andConv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition ofConv
andf
lead to 10000-times faster evaluation for numeric input.
$endgroup$
– Henrik Schumacher
15 hours ago
add a comment |
Your Answer
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1 Answer
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1 Answer
1
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oldest
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oldest
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oldest
votes
$begingroup$
Towards Question 2: Make it a finite sum in Conv
. Indeed, there are only finitely many nonzero summands. Or better use Dot
.
f2[s_, r_] := s^r UnitStep[s];
Conv2[s_, r_] := #.Reverse[#] &[f2[Range[0, s], r]]
m = 10;
aa = Outer[Conv, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
bb = Outer[Conv2, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
aa == bb
11.0072
0.001253
True
$endgroup$
$begingroup$
As I see you use==
on the values of Timings or ? Still, the main aim is to show thatMainIdentity[m_, n_] == n^(2m+1)+1
.
$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
I applied==
to the outputs ofConv
andConv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition ofConv
andf
lead to 10000-times faster evaluation for numeric input.
$endgroup$
– Henrik Schumacher
15 hours ago
add a comment |
$begingroup$
Towards Question 2: Make it a finite sum in Conv
. Indeed, there are only finitely many nonzero summands. Or better use Dot
.
f2[s_, r_] := s^r UnitStep[s];
Conv2[s_, r_] := #.Reverse[#] &[f2[Range[0, s], r]]
m = 10;
aa = Outer[Conv, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
bb = Outer[Conv2, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
aa == bb
11.0072
0.001253
True
$endgroup$
$begingroup$
As I see you use==
on the values of Timings or ? Still, the main aim is to show thatMainIdentity[m_, n_] == n^(2m+1)+1
.
$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
I applied==
to the outputs ofConv
andConv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition ofConv
andf
lead to 10000-times faster evaluation for numeric input.
$endgroup$
– Henrik Schumacher
15 hours ago
add a comment |
$begingroup$
Towards Question 2: Make it a finite sum in Conv
. Indeed, there are only finitely many nonzero summands. Or better use Dot
.
f2[s_, r_] := s^r UnitStep[s];
Conv2[s_, r_] := #.Reverse[#] &[f2[Range[0, s], r]]
m = 10;
aa = Outer[Conv, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
bb = Outer[Conv2, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
aa == bb
11.0072
0.001253
True
$endgroup$
Towards Question 2: Make it a finite sum in Conv
. Indeed, there are only finitely many nonzero summands. Or better use Dot
.
f2[s_, r_] := s^r UnitStep[s];
Conv2[s_, r_] := #.Reverse[#] &[f2[Range[0, s], r]]
m = 10;
aa = Outer[Conv, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
bb = Outer[Conv2, Range[0, m], Range[1, m]]; // AbsoluteTiming // First
aa == bb
11.0072
0.001253
True
answered 16 hours ago
Henrik SchumacherHenrik Schumacher
59.4k582165
59.4k582165
$begingroup$
As I see you use==
on the values of Timings or ? Still, the main aim is to show thatMainIdentity[m_, n_] == n^(2m+1)+1
.
$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
I applied==
to the outputs ofConv
andConv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition ofConv
andf
lead to 10000-times faster evaluation for numeric input.
$endgroup$
– Henrik Schumacher
15 hours ago
add a comment |
$begingroup$
As I see you use==
on the values of Timings or ? Still, the main aim is to show thatMainIdentity[m_, n_] == n^(2m+1)+1
.
$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
I applied==
to the outputs ofConv
andConv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition ofConv
andf
lead to 10000-times faster evaluation for numeric input.
$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
As I see you use
==
on the values of Timings or ? Still, the main aim is to show that MainIdentity[m_, n_] == n^(2m+1)+1
.$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
As I see you use
==
on the values of Timings or ? Still, the main aim is to show that MainIdentity[m_, n_] == n^(2m+1)+1
.$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
$begingroup$
How to check identity $(1)$ in main question ?
$endgroup$
– Petro Kolosov
15 hours ago
1
1
$begingroup$
I applied
==
to the outputs of Conv
and Conv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition of Conv
and f
lead to 10000-times faster evaluation for numeric input.$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
I applied
==
to the outputs of Conv
and Conv2
in order to check that the produce the same results. The timings are supposed to show you that the new definition of Conv
and f
lead to 10000-times faster evaluation for numeric input.$endgroup$
– Henrik Schumacher
15 hours ago
add a comment |
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$begingroup$
An important question: What is
0^0
for you?$endgroup$
– Henrik Schumacher
16 hours ago
1
$begingroup$
For Q1 you can use
PossibleZeroQ
to check if the difference between the expressions is zero: reference.wolfram.com/language/ref/PossibleZeroQ.html$endgroup$
– Roman
16 hours ago
$begingroup$
What's the purpose of
First
in[...] == First@FullSimplify[n^(2 m + 1) + 1, Assumptions -> n > 0]
. Not that it returns1
!$endgroup$
– Henrik Schumacher
15 hours ago
$begingroup$
@HenrikSchumacher I think now it is common agreement that $0^0 = 1$, I prefer to reffer it to Knuth's Concrete mathematics. Concerning
First
I dont really know Mathematica well, so I just entered my function into the pattern I found in one of my previous questions here$endgroup$
– Petro Kolosov
15 hours ago
1
$begingroup$
When
n
ork
is not numerical, the conditions2 k + 1 <= n
andk == n
are not evaluated andA[n,k]
evaluates to the first, unconditioned definition ofA
which is0
. So in total, your definition ofA
is not appropriate for symbolic evaluation.$endgroup$
– Henrik Schumacher
15 hours ago