The Prolog lexer does not recognize strings with an escaped (i.e., double) backslash.

For example the following code is valid Prolog:

writeln("abc\"def").
writeln("abc\\def").

When executed in Prolog the " and \ characters are escaped, so this results in

abc"def
abc\def

Pygments however detects a syntax error on the second line:

Note that the Github highlighter for Prolog does it right on the second line but now there is a problem in escaping " on the first line.

The behavior should be the same as in, e.g., Python:

print("abc\"def")
print("abc\\def")