In the book "Modules and Rings" by John Dauns he adopts the following notation in Exercises 1-5 (see attached)

"For additive groups A, B, C, D and we write

; "

Exercise 1 (i), (ii) and (iii)

The matrix ring R acts on the right R-module M whose elements are row vectors:

Find (i) all submodules of M (ii) all right ideals of R, indicating which of these are ideals

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Would be most grateful for help

Peter