2.5. Correcting Mistakes, part 2

Suppose you accidentally typed `ephalunt' instead of `elephant'. You can erase the mistakenly-asserted node with the SNePSUL command erase, which takes a node as an argument (UM§2.8): erase m2. To practice with this, we'll do the following:

First, assert a node with a misspelling.

Since this will be the second node you will have asserted, SNePS will call it `M2'.

Then erase M2

and assert what we wanted without any misspellings (be careful!):

(assert member Clyde class ephalunt)
(erase m2)
(assert member Clyde class elephant)

SNePS should have simply returned node M1, since we had already built it, and, by the Uniqueness Principle, SNePS does not build or assert nodes more than once (UM§3.1.2). Thus, instead of building another representation of the proposition that Clyde is an elephant, Cassie showed us that she already believed that.