[Source](http://www.mit.edu/~jnt/Papers/J012-86-intractable.pdf "Permalink to ") %PDF-1.4 % 98 0 obj <> endobj xref 98 7 0000000015 00000 n 0000000479 00000 n 0000000787 00000 n 0000000978 00000 n 0000001057 00000 n 0000010862 00000 n 0000000572 00000 n trailer <