A searchable Prolog language description online [closed]

Answer 1

You might want to use the following preprint of an
appendix of a book that is not the ISO core standard:

ISO Prolog: A Summary of the Draft Proposed Standard.
Michael A. Covington, 1993
http://www.uv.es/fbarber/prolog/isoprolog94_ps.Z
http://www.dropbox.com/s/kr1pbrfc1kqzdpq/isoprolog94_ps.Z

It is much shorter than the full ISO standard, but
it informally predates and covers almost the same.

Answer 2

The ISO standard is available for a very low price (currently USD 30 60) from the ANSI webstore as an INCITS document. There you also get the two corrigenda for free. See iso-prolog tag info for all current documents. Here is a comprehensive overview of all built-in predicates which includes Cor.1 and Cor.2.

If you want a printout version, the best is still to print above INCITS document yourself being aware that page 10 is missing (a page left intentionally blank) — otherwise odd pages are on the left side. The document is an A4 scan with two columns per page. The informal Annex A goes better in a separate binding. Instead, add the two corrigenda!

Alternatively, SAI sells hardcopies.