I don't think there's any slicing here...

In your first example, $a is set to the last element because a list in scalar context returns the last element. In your second example, you have a really oddball truth value thing. Ranges in scalar context do things I don't easily comprehend (read perlop for further info).

I'm really not sure what perl does with (a..c). I usually use strict which would not allow that and I usually use warnings, which would explain some other things you have working against you. I think 'a' and 'c' are strings in your example, not totally sure.

Here are some interesting examples:

use strict;
#use warnings;

my $x = (1,2,3); # $x is 3, list in scalar context
my @y = (4 .. 6); # @y is (4,5,6);
my $y = @y; # $y is 3, array in scalar context
my $z = 0 .. 0;  # $z is true
my $w = 1 .. 3;  # $w is false

print "$x, $y, $z, $w\n";
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You will get lots of warnings with the above if you turn on warnings.