When issuing the following code at the prompt… ?- X is 3, Y is 3. The following output appears: X = Y, Y = 3. I’d love a better understanding of what’s happening with that X=Y, and why it doesn’t say X=3. Is SWI-Prolog doing some kind of variable aliasing as an optimization?

Does SWI-Prolog do variable aliasing?

EricGT October 21, 2019, 10:16pm 2

Variable aliasing? No, because the variables are immutable.

Unification? Yes, Prolog uses syntactic unification

See this answer for more details.

1 Like

Topic		Replies	Views
Solving Systems of Equations with Prolog Help!	15	1573	March 17, 2022
Mystery Unification Help!	1	491	July 7, 2019
Unification Wiki	0	2216	May 21, 2019
Surprising result with equals dot dot Help! functor	16	1368	February 8, 2022
A Prolog Unparser Error Discussion	2	334	July 17, 2021