Without double entry system accounting systems are not effective ?

yes this statement is true. coz single entry system is not effective and it have alot of ifs and buts and result are very poor

I agree and double entry system is mandatory for any Accounting entry.

Assets = Liabilities + Equity is a very elegant mathematical equation. Making adjustments at any one variable must affect this equation and that is what creates both the elegance, necessity and result of the effectivness of double entry accounting.

To some extend I agree but accounting system still survice in single entry specially in development sector or the organizations working on grants...(where there is single source of income)

Most of the company including the small traders use the computerized accounting system which runs on the double entry accounting system.

So the concept of single accounting system by itself is scrape and therefore no point in discussing the issues which have no material value.

YES

The essential point of the double-entry system is to achieve a recording balance between related accounts.Because every transaction involves certain kinds of monetary exchanges between at least two business accounts, the term "double-entry system"

I agree and double entry system is mandatory for accounts

There is a single entry symtem accounting, i agreewith you.

Indeed, you are right!!

I agree