From a sequence of integers each of the sequences
for arbitrary integer can be obtained by one step. Is it possible to obtain from through a sequence of such steps?
From a sequence of integers each of the sequences
for arbitrary integer can be obtained by one step. Is it possible to obtain from through a sequence of such steps?
Answer: no.
Under all transformations allowed in the problem we have , but .
Remark. The transformations allowed in the problem are in fact the elementary transformations of the determinant
and the invariant is the absolute value of the determinant which is preserved under these transformations.
1. Define the invariant: For a quadruple , let denote . We will show that is invariant under the given transformations.
2. Check invariance under each transformation:
- For the transformation :
After transformation, we have:
- For the transformation :
After transformation, we have:
- For the transformation :
After transformation, we have:
- For the transformation :
After transformation, we have:
3. **Calculate for the initial and target quadruples**:
- For the initial quadruple :
- For the target quadruple :
4. Compare the invariants: Since is invariant under the given transformations, and the initial is 2 while the target is 1, it is impossible to transform into using the given transformations.
The final answer is False