Matrix equivalence and rank
About points...
We associate a certain number of points with each exercise.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.
That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.
That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.
About difficulty...
We associate a certain difficulty with each exercise.
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.
That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:
Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise
Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise
Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise
Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise
Level 5 -
Level 6 -
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.
That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:
Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise
Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise
Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise
Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise
Level 5 -
Level 6 -
Question
Solution
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Exercise:
Let Ain M_mtimes nK. Then exists Pin textGL_mK Qin textGL_nK s.t. PAQ leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where rtextcol-rankA. In particular textcol-rankAleq textminmn.
Solution:
Proof. Consider T_A:K^nlongrightarrow K^m T_AvA v. Then rtextcol-rankAtextdim ImT_A because we have seen that textImT_AtextSpT_Ae_...Te_ntextSptextcolumns of A. Now apply the previous proposition to T_A and we get that T_mathcalC^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright for some bases mathcalB of K^n and mathcalC of K^m. &Longrightarrow id_K^m_mathcalC^epsilon_m T_A_epsilon_m^epsilon_n id_K^n_epsilon_m^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where epsilon_n epsilon_m are the standard bases of K^n K^m respectively.
Let Ain M_mtimes nK. Then exists Pin textGL_mK Qin textGL_nK s.t. PAQ leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where rtextcol-rankA. In particular textcol-rankAleq textminmn.
Solution:
Proof. Consider T_A:K^nlongrightarrow K^m T_AvA v. Then rtextcol-rankAtextdim ImT_A because we have seen that textImT_AtextSpT_Ae_...Te_ntextSptextcolumns of A. Now apply the previous proposition to T_A and we get that T_mathcalC^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright for some bases mathcalB of K^n and mathcalC of K^m. &Longrightarrow id_K^m_mathcalC^epsilon_m T_A_epsilon_m^epsilon_n id_K^n_epsilon_m^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where epsilon_n epsilon_m are the standard bases of K^n K^m respectively.
Meta Information
Exercise:
Let Ain M_mtimes nK. Then exists Pin textGL_mK Qin textGL_nK s.t. PAQ leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where rtextcol-rankA. In particular textcol-rankAleq textminmn.
Solution:
Proof. Consider T_A:K^nlongrightarrow K^m T_AvA v. Then rtextcol-rankAtextdim ImT_A because we have seen that textImT_AtextSpT_Ae_...Te_ntextSptextcolumns of A. Now apply the previous proposition to T_A and we get that T_mathcalC^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright for some bases mathcalB of K^n and mathcalC of K^m. &Longrightarrow id_K^m_mathcalC^epsilon_m T_A_epsilon_m^epsilon_n id_K^n_epsilon_m^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where epsilon_n epsilon_m are the standard bases of K^n K^m respectively.
Let Ain M_mtimes nK. Then exists Pin textGL_mK Qin textGL_nK s.t. PAQ leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where rtextcol-rankA. In particular textcol-rankAleq textminmn.
Solution:
Proof. Consider T_A:K^nlongrightarrow K^m T_AvA v. Then rtextcol-rankAtextdim ImT_A because we have seen that textImT_AtextSpT_Ae_...Te_ntextSptextcolumns of A. Now apply the previous proposition to T_A and we get that T_mathcalC^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright for some bases mathcalB of K^n and mathcalC of K^m. &Longrightarrow id_K^m_mathcalC^epsilon_m T_A_epsilon_m^epsilon_n id_K^n_epsilon_m^mathcalB leftarray@c|c@ matrix I_r matrix & hline & matrix matrix arrayright where epsilon_n epsilon_m are the standard bases of K^n K^m respectively.
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