@vv This is OK, Thank you very much.

@Markiyan Hirnyk Yes, Thank you so much but I want its output be a list such as my example.

@Carl Love Thank you so much. I could remove it.

@acer I think that the second way is good for me.Thank you up to now.

@acer Thanks for these ways, But I want most fast way. Could you please send it?

@Markiyan Hirnyk I don't know why the tittle of my question is changed!!!

@Markiyan Hirnyk Thank you so much.

@Markiyan Hirnyk Thank you so much.

I am looking forward to hearing from you.

With the best regards,

MDD

@Markiyan Hirnyk Is there another commands for this? I want test them too.

@Preben Alsholm You are right. But in my study, parameters a, b, c,... can specialize in real number. I want one command that could conclude that when a^13b^17 is none zero then a<>0 and b<>0.

@Carl Love What is your idea about the following example?

false!!!

@Carl Love Thanks I think that the assuming command is better.

@Carl Love Therefore you suggest me to use assuming command in my procedure?

@Carl Love Thanks. I want use from above assume command (Kitonum answer) in my procedure. Can I use at middle of procedure from interface(showassumed= 0) command, automatically?

@Kitonum Thank you so much. When I use your answer and then type 'a' it is appears to form 'a~'. Why this is happen?