Please help me with this. Thank you The operation of differentiation does not apply to discrete-valued quantities, and thus a frequency-differentiation property for the FS or DTFS does not exist. However, a frequency- differentiation property does exist for the DTFT. Explain and comment supporting your explanation with the proper equations. Solution Frequency differentiation property exists for dtft because it converts discrete in time domain to continuous in frequency domain where as dtfs converts discrete in time domain to discrete in frequency domain.

1. please I need answers for these questions the book is Systems Analysis Design with UML v 2
Fourth Edition
Q1)- What is the relationship between level 0 and level 1 DFD diagrams? Explain.
Q2)- What does Use Case mean? and what does use case describe?
Q3)- What does triggers mean in use case, and what are the trigger types? and who's usually be
a trigger?
Q4)- Describe the best way to validate the content of use cases.
Q5)- What is the purpose of an intersection entity? Describe the steps used to create an
intersection entity?
Solution
R is an implementation of the S programming language combined with lexical scoping semantics
inspired by Scheme.[11] S was created by John Chambers while at Bell Labs. There are some
important differences, but much of the code written for S runs unaltered.[12]
R was created by Ross Ihaka and Robert Gentleman[13] at the University of Auckland, New
Zealand, and is currently developed by the R Development Core Team, of which Chambers is a
member. R is named partly after the first names of the first two R authors and partly as a play on
the name of S.[14] The project was conceived in 1992, with an initial version released in 1995
and a stable beta version in 2000