X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=appendix-a6.git;a=blobdiff_plain;f=parse;h=13fe2f23395fabb16bb0a9b15d3bc6496f9454ea;hp=7ca1ed6aa70817165ca476ac6323a37f4404506e;hb=454c5cdcf27ce0ac28aa9f62585387139690c779;hpb=708d36a1a95409c926ac4be1a343faa41cf09052;ds=sidebyside

diff --git a/parse b/parse
index 7ca1ed6..13fe2f2 100755
--- a/parse
+++ b/parse
@@ -27,6 +27,7 @@ while (<>) {
     s/\s+$//;
     next if m/^\s*\#/;
     next unless m/\S/;
+    next if m/^\s/;
     if (m/^([A-Z]+)\s*\=\s*(\S.*)$/) {
 	my ($choname, $desc) = ($1,$2);
 	my $cho = addchoice($choname, Desc => $desc);
@@ -57,7 +58,7 @@ our @vab;
 
 # Go through the voters and construct V(A,B)
 
-print "\nDefeats matrix\n";
+print "\nPreference matrix\n";
 
 foreach my $iv (@invotes) {
     my ($votestr,$voter) = @$iv;
@@ -147,31 +148,41 @@ foreach my $i (0..$#choices) {
     drop $i, "majority ratio ($vad * $majr->[1] <= $vda * $majr->[0])";
 }
 
-my $defeats = Graph::Directed->new; # A.6(4)
+print "\nDefeats A.6(4)\n";
+
+my $defeats = Graph::Directed->new;
 
 sub chremain () {
     return grep { !$ch[$_]{Dropped} } (0..$#ch);
 }
 
 foreach my $ia (chremain()) {
-    $defeats->add_vertex($ia);
+    $defeats->add_vertex($choices[$ia]);
     foreach my $ib (chremain()) {
 	my $vab = scalar @{ $vab[$ia][$ib] };
 	my $vba = scalar @{ $vab[$ib][$ia] };
 	next unless $vab > $vba;
-	print "defeat: $choices[$ia] beats $choices[$ib] ($vab > $vba)\n";
-	$defeats->add_vertex($ia,$ib);
+	my $diff = $vab - $vba;
+	print "defeat: $choices[$ia] beats $choices[$ib]",
+	    " ($vab > $vba: $diff)\n";
+	$defeats->add_edge($choices[$ia],$choices[$ib]);
     }
 }
 
+sub chvab ($$) {
+    my ($ca,$cb) = @_;
+    my $v = $vab[ $choices{$ca}{Index} ][ $choices{$cb}{Index} ];
+    return scalar @$v;
+}
+
 sub weaker ($$) {
     # A.6(7)(1)
     my ($def1,$def2) = @_;
-    my ($ia,$ix) = @$def1;
-    my ($ib,$iy) = @$def1;
-    return 1 if $vab[$ia][$ix] < $vab[$ib][$iy];
-    return 1 if $vab[$ia][$ix] == $vab[$ib][$iy]
-	&& $vab[$ix][$ia] > $vab[$iy][$ib];
+    my ($ca,$cx) = @$def1;
+    my ($cb,$cy) = @$def1;
+    return 1 if chvab($ca, $cx) < chvab($cb, $cy);
+    return 1 if chvab($ca, $cx) == chvab($cb, $cy)
+	&& chvab($cx, $ca) > chvab($cy, $cb);
     return 0;
 }
 
@@ -194,10 +205,10 @@ for (;;) {
 
     foreach my $ia (chremain()) {
 	foreach my $ib (chremain()) {
-	    next if $tdefeats->has_edge($ia,$ib);
-	    next if !$tdefeats->has_edge($ib,$ia);
+	    next if $tdefeats->has_edge($choices[$ia],$choices[$ib]);
+	    next if !$tdefeats->has_edge($choices[$ib],$choices[$ia]);
 	    print "not in Schwartz set: $choices[$ia] because $choices[$ib]\n";
-	    $schwartz->delete_vertex($ia);
+	    $schwartz->delete_vertex($choices[$ia]);
 	    last;
 	}
     }
@@ -207,6 +218,7 @@ for (;;) {
     our @weakest = ();
 
     foreach my $edge ($schwartz->edges()) {
+#	print " considering @$edge\n";
 	if (!@weakest) {
 	    # no weakest edges yet
 	} elsif (weaker($edge, $weakest[0])) {
@@ -222,14 +234,15 @@ for (;;) {
     }
 
     last unless @weakest;
-    
-    printf "weakest defeats %d > %d", 
-	(scalar @{ $vab[$_->[0]][$_->[1]] }),
-	(scalar @{ $vab[$_->[1]][$_->[0]] });
+
+    my $w = $weakest[0];
+    printf "weakest defeats %d > %d\n", 
+        chvab($w->[0], $w->[1]),
+	chvab($w->[1], $w->[0]);
     foreach my $weakest (@weakest) {
-	my ($ia,$ib) = @$weakest;
-	print "weakest defeat $choices[$ia] > $choices[$ib]\n";
-	$defeats->delete_edge($ia,$ib);
+	my ($ca,$cb) = @$weakest;
+	print "weakest defeat $ca > $cb\n";
+	$defeats->delete_edge($ca,$cb);
     }
 
     print "defeats within the Schwartz set, round again\n";
@@ -244,7 +257,7 @@ if ($schwartz->vertices() == 1) {
     print "WINNER IS ONE OF (CASTING VOTE DECIDES):\n";
 }
 
-printf "    %-5s %s\n", $choices[$_], $ch[$_]{Desc}
+printf "    %-5s %s\n", $_, $choices{$_}{Desc}
     foreach ($schwartz->vertices());
 
 print ".\n";