@habib i am not getting your 4th point ...
take this example this schedule is not serizable to any serial schedule becuase T2 is reading a data item A which is writen by T1 (T1-T2). so scheduling should be T1 to T2 but prbolem is this T2 is reading the data item B which is initial value of B so by this schedulig must be( T2-T1) so schedule is not serizable to any serial schedule. and this problem will exist if T2 is commited or not commited ..
you can give me any Referece for 4th point ?