Proof 2 lit on by ''burning the candle at both ends'', changing ''e''<sub>2</sub> into a normal form that reduced to ''e''<sub>4</sub>, and changing ''e''<sub>3</sub> into a normal form that also reduced to ''e''<sub>4</sub>, in this way tethering ''e''<sub>2</sub> and ''e''<sub>3</sub> to a common stake. In more detail, one route went from "(p (q))(p (r))" to "(p q r, (p))", and another went from "(p (q r))" to "(p q r, (p))", thus equating the two points of departure. | Proof 2 lit on by ''burning the candle at both ends'', changing ''e''<sub>2</sub> into a normal form that reduced to ''e''<sub>4</sub>, and changing ''e''<sub>3</sub> into a normal form that also reduced to ''e''<sub>4</sub>, in this way tethering ''e''<sub>2</sub> and ''e''<sub>3</sub> to a common stake. In more detail, one route went from "(p (q))(p (r))" to "(p q r, (p))", and another went from "(p (q r))" to "(p q r, (p))", thus equating the two points of departure. |