newRPL - build 1255 released! [updated to 1299]

[Claudio L.]

(12-20-2018 10:17 PM)The Shadow Wrote:  What sort of rule do I need to convince '2*X*Y-Y*X' to become 'X*Y'?

I thought this would do it (when followed with AUTOSIMPLIFY):

'.XN*.xX+.XM*.xX:→(.XN+.XM)*.xX'

since it's commutative. It doesn't work, however.

However, that rule *does* turn '2*X*Y+Y*X' to '(X+2*X)*Y'. Why won't it work on the subtraction?

New rules engine (3rd rewrite) is up and running on my system, I'll test some more before releasing in the wild and also add the variable attributes support we discussed above. Your example rule already produces the correct result '(2*Y-Y)*X' which AUOSIMPLIFY quickly turns into Y*X. The new engine uses much more RAM but does proper backtracking. The previous generation tried to cut corners to save RAM but cases like the one above were failing to test all possible permutations.
AUTOSIMPLIFY already has 8 independent groups of rules, controlled by 8 independent flags to disable/enable the simplifications.
We still have to come up with what the groups mean but the first one is custom user rules (in a variable 'AUTOSIMPLIFY.RULES'), the second group is basic cleanup rules, 3rd group is division/negative powers simplification (this can remove poles from an expression), and the rest are yet to be defined (blank for now, we'll fill them up with community input over the years).