protocol

tabu_search_problem_protocol

Protocol for tabu search problem definitions. A problem object must define the three required predicates and may optionally define predicates to override neighbor generation with delta energy, full neighborhood enumeration, stopping, and progress reporting defaults.

Availability:
logtalk_load(tabu_search(loader))
Author: Paulo Moura
Version: 1:0:0
Date: 2026-08-15
Compilation flags:
static
Dependencies:
(none)
Remarks:
(none)
Inherited public predicates:
(none)

Public predicates

initial_state/1

Returns an initial state for the optimization problem.

Compilation flags:
static
Template:
initial_state(State)
Mode and number of proofs:
initial_state(-nonvar) - one

neighbor_state/2

Generates a neighboring state from the given state. This is the most problem-specific predicate and its definition determines the quality of the search. Used both for candidate sampling and (when neighbors/2 is not defined) as the sole neighborhood operator.

Compilation flags:
static
Template:
neighbor_state(State,Neighbor)
Mode and number of proofs:
neighbor_state(+nonvar,-nonvar) - one

neighbor_state/3

Generates a neighboring state and returns the energy change (delta) directly, avoiding a full energy recomputation. Optional. When not defined by the problem, the algorithm calls neighbor_state/2 and state_energy/2 instead.

Compilation flags:
static
Template:
neighbor_state(State,Neighbor,DeltaEnergy)
Mode and number of proofs:
neighbor_state(+nonvar,-nonvar,-number) - one

neighbors/2

Optionally returns the complete list of neighboring states. When defined, the algorithm uses this list (or a random sample of it controlled by the candidates(N) option) instead of repeated calls to neighbor_state/2. Useful for small, enumerable neighborhoods.

Compilation flags:
static
Template:
neighbors(State,Neighbors)
Mode and number of proofs:
neighbors(+nonvar,-list(nonvar)) - zero_or_one

state_energy/2

Computes the energy (cost) of the given state. The algorithm minimizes this value.

Compilation flags:
static
Template:
state_energy(State,Energy)
Mode and number of proofs:
state_energy(+nonvar,-number) - one

stop_condition/3

True when the search should stop given the current step, best energy found so far, and current energy. Optional. When not defined by the problem, the search runs until the maximum number of steps is reached.

Compilation flags:
static
Template:
stop_condition(Step,BestEnergy,CurrentEnergy)
Mode and number of proofs:
stop_condition(+non_negative_integer,+number,+number) - zero_or_one

progress/5

Called periodically to report optimization progress. Optional. When not defined by the problem, progress reporting is skipped. The acceptance and improvement rates are values between 0.0 and 1.0 computed over the interval since the last progress report.

Compilation flags:
static
Template:
progress(Step,BestEnergy,CurrentEnergy,AcceptanceRate,ImprovementRate)
Mode and number of proofs:
progress(+non_negative_integer,+number,+number,+number,+number) - zero_or_one

Protected predicates

(none)

Private predicates

(none)

Operators

(none)