A triangular matrix is not necessarily nilpotent. A triangular matrix is nilpotent if and only if all its diagonal entries are zero. This means that for a triangular matrix to be nilpotent, it must be an upper or lower triangular matrix with all zero diagonal entries. **

A strictly upper triangular matrix that is nilpotent is a matrix where all the entries below the main diagonal are zero, and all the entries on the main diagonal are also zero. This means that the matrix is upper triangular and all its eigenvalues are zero. Since the matrix is nilpotent, there exists a positive integer k such that the matrix raised to the power of k is the zero matrix. **

Not necessarily. A nilpotent matrix is a square matrix where some power of the matrix is the zero matrix. This means that the diagonal entries of a nilpotent matrix could be non-zero, as long as the matrix raised to a certain power results in a zero matrix. So, the diagonal entries of a nilpotent matrix are not necessarily equal to 0. **

To determine the matrices with respect to a nilpotent mapping, one can start by finding the minimal polynomial of the mapping. The minimal polynomial will give the characteristic equation, which can be used to find the eigenvalues of the mapping. Once the eigenvalues are known, the corresponding eigenvectors can be found, and the matrices can be constructed using these eigenvectors. The matrices will then represent the nilpotent mapping with respect to a chosen basis. **

The popularity of cycling or skiing can vary depending on the location and time of year. In general, cycling tends to be more popular in urban areas and during the warmer months, while skiing is more popular in mountainous regions and during the winter. However, it's difficult to determine which activity is followed more overall without specific data on participation rates in different regions and seasons. **

The excitement level of ice hockey versus soccer is subjective and can vary depending on personal preferences. Ice hockey is known for its fast-paced, physical nature with constant action and scoring opportunities. On the other hand, soccer is a more strategic game with longer periods of build-up play and intense moments during goal-scoring opportunities. Both sports have passionate fan bases and offer unique thrills, making it difficult to definitively say which is more exciting. **

It is highly unlikely that soccer will replace American football, basketball, baseball, and ice hockey as the most popular sports in the USA. These sports have deep-rooted cultural and historical significance in American society, and they have large and dedicated fan bases. Additionally, American football, basketball, baseball, and ice hockey have well-established professional leagues and infrastructure in the USA, which would make it difficult for soccer to overtake them in popularity. While soccer has been growing in popularity in the USA, it is more likely to continue to coexist alongside these other sports rather than replace them. **

Ice hockey is often perceived as more brutal than soccer due to the physical nature of the sport, which includes body checking and fighting. However, both sports have their own unique physical demands and risks of injury. While ice hockey may have more violent collisions, soccer players also face the risk of serious injuries such as concussions and ACL tears. Ultimately, the level of brutality in each sport can vary depending on the intensity of the competition and the actions of the players involved. **