to have +V3

[aliii]

It is written in the books (but i don't know that it is certain) that we can't start the sentence with 'to have +v3'.

For example;

.To have smoked is dangerous. (Is it incorret?)

.Having smoked is dangeours. (Is is correct?)

[5jj]

It is written in the books (but i Idon't know that it is certain) that we can't start the sentence with 'to have +v3'......Which books might that be?

To have smoked is dangerous. (Is it incorrect?)
.Having smoked is dangeours. (Is is correct?)

Your sentences are not very natural, but the first construction is certainly possible:

To have lived in Paris when one is young is to have lived.

[Tdol]

It is written in the books

Could you give references for this, please?

[emsr2d2]

It is written in the books (but i don't know that it is certain) that we can't start the sentence with 'to have +v3'.

For example;

.To have smoked is dangerous. (Is it incorret?)

.Having smoked is dangeours. (Is is correct?)

As requested, please give more context. Also please note:

1. Always capitalise the word "I" (first person singular)
2. I don't know why you have used a full stop before the first word of your two examples. Perhaps you meant to number them, as I have done here. If so, you need to put a space after the full stop (as you do after almost all full stops.)

[BobK]

Aside: I think some word-processing systems interpret a sentence immediately following a full stop as an element of a bulleted list, and people who use such support get into bad habits. Then people with no such support do the same, and the bad practice spreads.

b