Dear All, I'm puzzled as to why TLC gives me an error when checking the following. I'm aware that the two lines before the commented-out line and the commented-out line are not equivalent. What I don't understand is why TLC give the error message: In evaluation, the identifier carts is either undefined or not an operator. line 12, col 45 to line 12, col 49 of module Dummy1 The location is the first occurrence of carts' in the Next action. Thanks in advance for help with this. Best regards, Marko ------------------------------- MODULE Dummy1 ------------------------------- EXTENDS Integers, Sequences VARIABLES carts, count, item Customer == 1..3 MaxBag == 10 Items == 1..10 Init == /\ carts = [c \in Customer |-> <<>>] /\ count = 1 /\ item = 1 Next == /\ \A c \in Customer \ {(count % 3) + 1}: carts'[c] = carts[c] /\ carts'[(count % 3) + 1] = carts[(count % 3) + 1] \o <<item, count>> \* /\ carts' = [carts EXCEPT ![(count % 3) + 1] = @ \o <<item, count>>] \* this does not cause an error /\ count' = count + 1 /\ item' = item + 1 ============================================================================= -- You received this message because you are subscribed to the Google Groups "tlaplus" group. To unsubscribe from this group and stop receiving emails from it, send an email to tlaplus+unsubscribe@xxxxxxxxxxxxxxxx. To view this discussion on the web visit https://groups.google.com/d/msgid/tlaplus/874l0xwxc2.fsf%40tpad-m.i-did-not-set--mail-host-address--so-tickle-me.
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