Reputation
666
Top tag
Next privilege 1,000 Rep.
Create new tags
 Dec 16 answered Combinatorial proof of summation of $\sum_{k = 0}^n {n \choose k}^2= {2n \choose n}$ Aug 31 awarded Yearling May 31 revised What's an intuitive way to think about the determinant? edited body Apr 21 answered Proving or disproving $c-d|p(c)-p(d)$ where $p$ is a polynomial. Dec 29 awarded Nice Answer Dec 20 awarded Constituent Dec 16 awarded Caucus Nov 11 comment “Number of zeroes of $f \leq \deg f$” used in a proof. Gern geschehen! Nov 11 comment “Number of zeroes of $f \leq \deg f$” used in a proof. Non-zero polynomials certainly are. Nov 11 answered “Number of zeroes of $f \leq \deg f$” used in a proof. Nov 9 comment If $A,B$ are commuting diagonalizable complex matrices , then $A,B$ have a common eigen-basis ? First prove the following: If $AB = BA$, then each eigenspace of $A$ is preserved by $B$. Apr 16 comment Construct matrix of ones and zeros based on sequences yes, your comment to the question is not off the mark - indeed such a matrix need not always exist. On the other hand, the Gale-Ryser theorem gives a necessary and sufficient condition for its existence for general sequences. Apr 16 comment Construct matrix of ones and zeros based on sequences If they don't sum up to the same constant, then the answer is somewhat trivially no, because the sums of both sequences will be the total number of $1$'s in the matrix. Apr 16 comment Construct matrix of ones and zeros based on sequences Then I am missing something. Apr 16 awarded Organizer Apr 16 revised Construct matrix of ones and zeros based on sequences Added a couple of tags Apr 16 suggested approved edit on Construct matrix of ones and zeros based on sequences Apr 16 answered Construct matrix of ones and zeros based on sequences Mar 15 comment If $AB=BA$ then they are diagonal This is clearly false, take $A$ arbitrary and $B=A$. There is however, a statement that if $A$ and $B$ are diagonalizable and $AB=BA$ then $A$ and $B$ are simultaneously diagonalizable. Feb 20 comment Suppose H and K are subgroups of a group G. If |H| = 12 and |K| = 35, what is |H intersection K|? What can the cardinality of $H\cap K$ be?