There is a problem with the sample in chapter "The Witness Problem"

[glishijie]

URL: https://souffle-lang.github.io/aggregates#the-witness-problem

The second sample has a problem, it has no "Witness Problem Error".

.decl family(name:symbol, age:number)
.decl youngest(name:symbol, age:number)

family("Alissa", 10).
family("Maria", 46).
family("Mark", 50).

youngest(p, n) :- n = min x : family(p, x).

Souffle version info:

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Version: 2.3-179-g8aae5218d
Word size: 32 bits
Options enabled: ffi ncurses sqlite zlib
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Copyright (c) 2016-22 The Souffle Developers.
Copyright (c) 2013-16 Oracle and/or its affiliates.
All rights reserved.
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[quentin]

Souffle is able to ground a witness for min and max in this case:

https://github.com/souffle-lang/souffle/blob/da9e3c24d15580b614b994eb4a39627a69516679/src/ast/transform/GroundWitnesses.h#L27-L41C1

[quentin]

duplicates:
souffle-lang/souffle#2135
souffle-lang/souffle#1801