huck has shown why your regex (correctly!) matches a single space. Here's the approach I would take to a solution. (Note that I am sure there are CPAN modules to do all this much better!) Pay particular attention to adding test cases to the no-match section of tests. I would also add some mixed-case tests to the all-match section. 

c:\@Work\Perl\monks>perl -wMstrict -le
"use Test::More 'no_plan';
 use Test::NoWarnings;
 ;;
 my $rx_1_3  = qr{ (?i) i{1,3} }xms;
 my $rx_1_9  = qr{ (?i) (?: $rx_1_3 | iv | v $rx_1_3? | ix) }xms;
 my $rx_1_39 = qr{ (?i) (?: $rx_1_9 | x{1,3} $rx_1_9?) }xms;
 ;;
 my $pat = qr{ [(]? \b $rx_1_39 \b (?: [.] | [)][.]?) [ ] }xms;
 ;;
 use constant ROMAN_1_39 => qw(
      i    ii    iii    iv    v     vi    vii    viii    ix   x
     xi   xii   xiii   xiv   xv    xvi   xvii   xviii   xix  xx
    xxi  xxii  xxiii  xxiv  xxv   xxvi  xxvii  xxviii  xxix xxx
   xxxi xxxii xxxiii xxxiv xxxv  xxxvi xxxvii xxxviii xxxix
   );
 ;;
 note 'perl version: ', $];
 ;;
 my $test_regex = qr{ \A $pat \z }xms;
 note 'test regex: ', $test_regex;
 ;;
 note 'ALL must match';
 for my $roman (ROMAN_1_39, map uc, ROMAN_1_39) {
   for my $pre ('', '(') {
     for my $post (qw/. ) )./) {
       my $rs = qq{$pre$roman$post };
       ok $rs =~ $test_regex, qq{'$rs'};
       }
     }
   }
 ;;
 note 'NONE shall pass!';
 for my $nomatch (ROMAN_1_39, ' ',
   qw(iiii ixxxix xxxixi ixxxixi etc),
   ) {
   ok $nomatch !~ $test_regex, qq{'$nomatch'};
   }
 ;;
 done_testing;
"

[download]
(I won't pollute these sacred spaces with the rather tedious output.)

Give a man a fish:  <%-{-{-{-<

In reply to Re: Pattern Matching by AnomalousMonk
in thread Pattern Matching by davidas

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