       NOTE: This disposition is nonprecedential.

  United States Court of Appeals
      for the Federal Circuit
               __________________________

                 (Serial No. 10/259,203)
            IN RE RAVI VAIDYANATHAN
              __________________________

                       2009-1404
               __________________________

    Appeal from the United States Patent and Trademark
Office, Board of Patent Appeals and Interferences, No.
2008-2867.
              ___________________________

                 Decided: May 19, 2010
              ___________________________

    BRIAN M. KOLKOWSKI, Orbital Research Inc., of Cleve-
land, Ohio, for appellant.

    RAYMOND T. CHEN, Solicitor, Office of the Solicitor,
United States Patent and Trademark Office, of Arlington,
Virginia, for the Director of the United States Patent and
Trademark Office. With him on the brief were BENJAMIN
D.M. WOOD and NATHAN K. KELLEY, Associate Solicitors.
                __________________________

 Before MICHEL, Chief Judge, NEWMAN AND DYK, Circuit
                        Judges.
  Opinion for the court filed by Circuit Judge NEWMAN.
IN RE VAIDYANATHAN                                        2

  Circuit Judge DYK concurs in the judgment.


NEWMAN, Circuit Judge.
    Ravi Vaidyanathan (“the applicant”) appeals the rul-
ing of the Board of Patent Appeals and Interferences of
the United States Patent and Trademark Office, affirming
the examiner’s rejection of claims 1–9 of application Serial
No. 10/259,203 (“the ’203 application”), on the ground of
obviousness, 35 U.S.C. §103(a). The Board reversed the
rejection of claims 10–11. Ex parte Vaidyanathan, No.
2008-2867 (B.P.A.I. March 11, 2009) (“Board Opinion”).
     For claims 1–9, we vacate the rejection and remand
for further examination.
                       DISCUSSION
    The ’203 application relates to a guidance and control
method for controlling munitions such as missiles or
unmanned aircraft, wherein an autonomous reflex re-
sponse is based on a neural network model of a biological
response. The method is designed for the “endgame”
stage of flight when the munition is very close to the
target, at which stage the system guides and controls the
munition by calculating trajectory commands using a
neural network that is trained using a genetic algorithm;
the neural network provides “high level” guidance com-
mands to an autopilot, which converts those commands to
signals that direct the actual movement of the munition.
The system is described as achieving substantial gains in
accuracy, as compared with prior systems.
    The ’203 specification acknowledges extensive existing
knowledge concerning guided munitions, the use of auto-
pilots in connection with these munitions, and the devel-
opment of neural networks.          The ’203 invention
contemplates that known technologies are used to bring
the munition within close range of the target, at which
3                                         IN RE VAIDYANATHAN

stage the neural network provides rapid-response trajec-
tory commands for the final or endgame stage. The
specification describes in mathematical detail a form of
neural network that is modeled on the rapid neural
response that is described as characteristic of the escape
actions seen in cockroaches.
    Claim 1, the broadest claim on appeal, is as follows:
    1. A method of controlling a munition, vehicle or
    aircraft comprising the steps of:
    a) receiving information from sensors;
    b) processing the information with a neural net-
    work to obtain a desired trajectory for the muni-
    tion, vehicle or aircraft to follow;
    c) inputting the desired trajectory and the in-
    formation from internal sensor into an autopilot;
    and
    d) controlling the munition, vehicle or aircraft to
    fly the desired trajectory through the autopilot.
Claims 2–7 include additional limitations that are not
argued separately in this appeal, although claim 3, which
requires that the “neural network is trained using a
genetic algorithm,” is discussed. Claims 8 and 9 add the
limitations that the neural network guides the munition,
vehicle or aircraft “to avoid a target” (claim 8) or “to strike
a target” (claim 9). Claims 10 and 11, which were allowed
by the Board, add the limitations that the neural network
only guides the munition “during the last less than about
1 second” before either target avoidance (claim 10) or
target strike (claim 11); these claims are not part of this
appeal.
    The Board affirmed the examiner’s rejection of claims
1, 2, and 4–9 as obvious in view of the combination of two
references, U.S. Patent No. 6,473,747 (“Biggers”) and No.
IN RE VAIDYANATHAN                                        4

5,435,503 (“Johnson”). Claim 3 was rejected in view of
Biggers, Johnson, and U.S. Patent No. 6,449,603
(“Hunter”). The applicant argues that these rejections
were based on a misunderstanding of the Biggers and
Johnson references, and lacked sufficient findings by the
Board. The applicant states that the Board misinter-
preted claims 8 and 9, leading the Board to conclude
erroneously that the additional limitations in these claims
were taught by Biggers. The applicant complains that
neither the examiner nor the Board made sufficient
findings or adequately explained their reasoning. The
PTO, through the Solicitor on this appeal, now seeks to
substitute new reasoning for that supplied by the Board
concerning how the asserted references should be inter-
preted. The applicant attempted to respond to these new
arguments in his Reply Brief.
                             I
    The obviousness inquiry is decided as a matter of law,
based on four general factual inquiries as explained in
Graham v. John Deere Co., 383 U.S. 1, 17–18 (1966), and
reaffirmed in KSR International, Inc. v. Teleflex, Inc., 550
U.S. 398, 406–07 (2007). The patent examiner is respon-
sible for marshalling the references whose teachings are
most relevant to the claimed invention, and evaluating
the claimed invention against these teachings, from the
viewpoint of a person of ordinary skill in the field of
invention. See Graham, supra; In re Kubin, 561 F.3d
1351, 1355 (Fed. Cir. 2009); see generally In re Oetiker,
977 F.2d 1443, 1445–47 (Fed. Cir. 1992).
    The applicant challenges the Board’s legal and factual
analyses. He argues that the Board committed legal error
by failing to follow the Court’s requirement that the
factual findings on which the legal conclusion of obvious-
ness rests should be set forth explicitly. See KSR, 550
U.S. at 418 (“To facilitate review, this analysis should be
5                                        IN RE VAIDYANATHAN

made explicit.”); see also In re Gartside, 203 F.3d 1305,
1314 (Fed. Cir. 2000) (“We have expressly held that the
Board’s opinion must explicate its factual conclusions,
enabling us to verify readily whether those conclusions
are indeed supported by ‘substantial evidence’ contained
within the record.”); In re Grasselli, 713 F.2d 731, 739
(Fed. Cir. 1983) (“It is fundamental that rejections under
35 U.S.C. §103 must be based on evidence comprehended
by the language of that section.”).
    The applicant points to the Board’s interpretation of
the Biggers and Johnson references as examples of the
Board’s failure accurately to ascertain the differences
between the prior art and the claimed invention, as
required by Graham. He also states that the Board failed
to establish, or even to address at all, the level of ordinary
skill in the field of the invention, as required by Graham.
He also states that the Board erred in its interpretation of
claims 8 and 9, further undermining the conclusion of
obviousness. He contends that these errors so infect the
Board’s legal analysis of obviousness that the rejections
cannot stand.
                              A
    The applicant first argues that the Board’s interpreta-
tion of the Biggers reference lacks support by substantial
evidence. The applicant points out that the Board viewed
Biggers differently than did the examiner, and that the
PTO Solicitor has attempted yet a third interpretation on
this appeal. We agree that the PTO has offered divergent
views of what Biggers describes and means in relation to
the ’203 application.
    Biggers is directed to the control of a guided missile
using a neural network that processes information re-
ceived from onboard sensors to determine desired trajec-
tory commands. Unlike the ’203 application’s emphasis
on the endgame stage of flight, Biggers uses the neural
IN RE VAIDYANATHAN                                      6

network at an intermediate stage of flight, and then
switches to an independent guidance control system for
the late-stage approach to the target. Figures 3 and 4 of
Biggers illustrate the method: Figure 3 is a “data flow
diagram” showing the information received by and pro-
duced by a neural network (20), and Figure 4 is a “flow-
chart” depicting the sequence of steps by which the
system operates: 1




   1    In these figures “N.N.” stands for neural network,
“MSL” for missile, “A/C” for aircraft, and “A of A” for
angle of attack.
7                                          IN RE VAIDYANATHAN

As depicted in Figure 4, after missile launch (62) the
neural network receives missile position and velocity
information (64), target position and velocity information
(66), and time elapsed since launch information (68). At
decision block (70) the system determines whether the
missile is a safe distance from the aircraft; if it is not, a
zero signal is sent to the autopilot (72) and the autopilot
controls flight. If so, the neural network outputs a calcu-
lated angle-of-attack command that guides the missile
(78), unless, at decision block (76), it is determined that
the missile is close enough to its target to be transferred
to a separate guidance system (82). In that case, the
neural network ceases to provide commands and the
guidance system controls the missile’s flight. Thus the
Biggers neural network controls flight only during the
intermediate stage when the missile is a safe distance
away from the launching aircraft but not yet within close
range of its target.
   The applicant especially criticizes the Board’s third
Finding of Fact (“FF3”), which relates to the interplay
between the neural network component and the autopilot
component of the Biggers system. The Board stated:
    FF3 Biggers teaches sending angle of attack
        commands to the auto pilot system of the
        missile. Biggers, col. 4, l. 66 to col. 5, l. 2.
        Although flow diagram box 44 in fig. 3 of
        Biggers is not explicitly discussed by Big-
        gers, a person of ordinary skill in the art
        would understand that box to denote the
        auto pilot alluded to by Biggers.
Board Opinion at 6. This finding is relevant to step (c) of
claim 1 of the ’203 application, where the desired trajec-
tory calculated by the neural network in step (b) is input
into an autopilot. The Board found that the trajectory or
“angle of attack” commands generated by the Biggers
neural network are sent to the autopilot for implementa-
IN RE VAIDYANATHAN                                            8

tion, and thus that this aspect of step (c) is taught by
Biggers. The Board did not discuss Biggers Figure 4, or
the Biggers specification (apart from the cited sentence at
col.4 l.66 to col.5 l.2, which makes no reference to the
neural network), but cited box (44) of Figure 3 as provid-
ing implicit support for this aspect, although “not explic-
itly discussed.” See FF3, supra. Box (44) shows “angle of
attack” trajectory commands as output of the neural
network, but makes no mention of an autopilot.
    The Board thus recognized that the relay of trajectory
commands from the neural network to the autopilot is not
described explicitly in Biggers, but stated that “a person
of ordinary skill in the art of missile guidance would
understand that trajectory angle of attack commands, by
whatever means they are produced, are transmitted to a
missile auto pilot, which specifies angle changes to the
missile necessary to maintain the velocity vector of the
missile along the specified trajectory and transmits these
changes to an alignment/control system to effect the
changes.” Board Opinion at 9–10. The Board cited no
other evidence indicating the level of ordinary skill in the
relevant art, or explaining why a person of ordinary skill
would view this autopilot aspect as an implicit teaching of
Biggers.
    The applicant states that Biggers teaches the use of
three independent, discrete elements or systems to guide
the missile in different stages of flight. The applicant
refers to the specific portions of the Biggers specification
that he states describe these three distinct elements and
stages: (1) an autopilot used only to maintain the initial
trajectory after launch and until the missile is a safe
distance from the aircraft that launched it (Biggers, col. 4
l.66 to col. 5 l.2); (2) a neural network apparatus for
taking over control of the trajectory of the missile after it
is a safe distance from the aircraft until it reaches a non-
final position (id. col. 4 ll.13–17; col. 6 ll.43–44); and (3) a
9                                         IN RE VAIDYANATHAN

terminal guidance system for guiding the missile from
that non-final position to a final position (id. col. 4 ll. 15–
17; col. 4 ll.35–38; col. 5 ll.14–17).
    The applicant states that when it is understood that
Biggers teaches these separate and independent systems
for guiding the missile at different stages, it cannot rea-
sonably be concluded that Biggers teaches that the neural
network sends its trajectory commands to the autopilot.
He states that Biggers only refers to the autopilot in
connection with the initial stage, before the neural net-
work begins to control flight. He argues that the Biggers
specification never states that the neural network sends
its commands to the autopilot, and that this path would
be incompatible with the purpose of the Biggers inven-
tion. He states that Figure 3, cited by the Board, provides
no support for the Board’s interpretation, for it makes no
mention of an autopilot, and box (44) represents informa-
tion that is produced by the neural network rather than a
separate autopilot component of the system. The appli-
cant argues that the flowchart in Figure 4 clarifies the
independent operation of the autopilot and the neural
network at different temporal stages. He states that
Figure 4 shows that the Biggers autopilot controls flight
only in the initial stage, when the missile is not yet a safe
distance from the launching aircraft, and that the provi-
sion of “zero A of A command” during this stage, at step
(72), indicates that the autopilot does not guide flight
based on information received from the neural network.
In contrast, Figure 4 shows that the neural network
calculates and outputs angle of attack commands in the
intermediate stage when it guides flight, as indicated in
step (78).
    The PTO Solicitor on this appeal simply states that
“substantial evidence supports the Board’s finding that
block 44 of Figure 3 denotes the missile’s autopilot sys-
tem.” PTO Brief at 18. This statement is not tied to any
IN RE VAIDYANATHAN                                       10

description within Figure 3, or any language in the speci-
fication, or any other source of “substantial evidence.”
Apparently recognizing this gap, the Solicitor also pre-
sents an explanation of Biggers that differs from that
provided by the Board. The Solicitor now states that
Biggers’ Figure 4 provides support for finding that Big-
gers teaches the input of trajectory information produced
by the neural network into an autopilot, which then
controls the missile to fly the desired trajectory. Contra-
dicting the applicant’s explanation of Biggers, the PTO
reasons that the “zero A of A command” sent to the auto-
pilot in step (72) is itself a “trajectory command” provided
by the neural network in the sense required by the appli-
cant’s claim 1 step (c). However, neither the Board nor
the Examiner made such findings regarding step (72), and
the Board’s opinion states that the Board found Biggers’
autopilot teaching not in Figure 4, but in block (44) of
Figure 3. The PTO Solicitor now argues, for the first
time, that Figure 4 is sufficient to show that commands
from the neural network are input into the autopilot in at
least one phase of the Biggers method.
    The PTO also argues that the Johnson reference de-
scribes an autopilot that receives and implements guid-
ance commands from a guidance function, and that this is
evidence of how traditional autopilots were known to
function. The Solicitor states, citing the “Background”
discussion in the ’203 specification, that autopilots have
operated in this way for over sixty years, since the Pro-
portional Navigation (“ProNav”) algorithm for terminal
stage missile guidance was introduced publicly in 1948.
The Solicitor states that while the Biggers reference lacks
detail in its description of the autopilot, nothing in Big-
gers suggests that these known autopiloting techniques
were set aside, or that the autopilot plays no role in
effectuating the trajectory commands calculated by the
Biggers neural network. The Solicitor argues: “Because
11                                      IN RE VAIDYANATHAN

the focus of Biggers is on what generates the guidance
commands—the neural network trajectory controller—
and not on how a missile converts these commands into
actual course changes, it is not particularly surprising
that Biggers does not discuss the autopilot in greater
detail.” PTO Brief at 21.
    The applicant addresses these new PTO arguments in
his Reply Brief. He states that Figure 4 of Biggers and
the general background knowledge of autopilots do not
show what the Solicitor states is shown. The applicant
points out that while the Solicitor states that in Biggers
“the neural network sends a zero angle of attack to the
autopilot” in step (72), nothing in either Figure 4 or the
accompanying description states that it is the neural
network that sends this zero angle of attack. Biggers
describes this step of Figure 4 as follows: “If [the missile]
is not a safe distance, then block 72 is processed wherein
a zero angle of attack command is sent to the auto pilot
system of the missile, and subsequently block 74 is exe-
cuted wherein the neural network waits a predetermined
amount of time . . . .” Biggers, col.4 l.67 – col.5 l.4. The
applicant contends that this description shows that the
neural network does not participate in guiding flight
during the initial stage. He argues that in contrast, step
(78) expressly shows the role played by the neural net-
work when it participates in flight guidance. He states
that there is no evidence supporting the Solicitor’s new
argument that the neural network’s participation is
inherent at step (72).
    The Solicitor states that the applicant has not ex-
plained where else the zero angle of attack in step (72)
could come from, but the applicant responds that he does
not bear the burden of proving what Biggers teaches. The
applicant points to the conflicting views of the Examiner,
the Board, and now the PTO Solicitor as indications that
the Biggers reference does not present the clarity of
IN RE VAIDYANATHAN                                        12

disclosure that the Solicitor now suggests. For example,
the Examiner’s Answer stated that “Biggers . . . explicitly
teaches that the path from the non-final position to the
final position should be calculated by the ‘neural network
apparatus’ and should be provided (or inputted) from the
neural network apparatus to the guidance system.”
(Emphasis in original.) The Board contradicted the
Examiner, and stated “We find no teaching in Biggers
that the trajectory data produced by the neural network
are sent to the missile guidance system.” Board Opinion
at 6. The Board instead relied on FF3, which also de-
parted from the Examiner’s fact finding, for the Examiner
had concluded that the “guidance system” of Biggers
“should be reasonably understood as an autopilot system,”
whereas the Board viewed the autopilot and guidance
systems of Biggers as separate functionalities. The PTO
Solicitor now retreats from the Board’s finding that
Biggers teaches that the trajectory commands produced
by the neural network are input into a separate autopilot
function; the Solicitor instead argues that autopilot
functions were well known, and that neither Biggers nor
the claimed invention altered the basic understanding of
autopilot functions.
    Thus the PTO has now provided a third explanation of
why Biggers teaches the input of trajectory commands
from the neural network into the autopilot—one to which
the applicant had no opportunity to respond or provide
rebuttal evidence before the Board, although he has
attempted to respond in his Reply Brief on this appeal.
This third retooling of the PTO position, without addi-
tional development of the record, casts serious doubt upon
the sufficiency of the support for any set of findings relat-
ing to the teachings of Biggers. Although the Solicitor
argues that the court must defer to the PTO’s latest
position, the agency’s contradictory findings of technologi-
cal facts based on shifting perceptions of the prior art
13                                      IN RE VAIDYANATHAN

impeach the deference normally owed to administrative
findings of fact. See Universal Camera Corp. v. NLRB,
340 U.S. 474, 496 (1951) (“evidence supporting a conclu-
sion may be less substantial when an impartial, experi-
enced examiner who has observed the witnesses and lived
with the case has drawn conclusions different from the
Board’s than when he has reached the same conclusion”).
    Further, the PTO’s new explanation cannot of itself
provide substantial evidence for the Board’s findings, for
our review is constrained by the facts that were developed
during the Board proceeding. While the PTO Solicitor’s
argument is new as to what portion of Biggers provides
support for the Board’s findings, we have occasionally
permitted the Solicitor to support the Board, on appeal to
the court, by reference to additional portions of the refer-
ences of record, provided that the applicant has had a fair
opportunity to respond. See In re Hedges, 783 F.2d 1038,
1039 (Fed. Cir. 1986); see also In re Wesslau, 353 F.2d
238, 241 (CCPA 1965) (prior art reference should be
considered in its entirety for what it fairly suggests to one
skilled in the art). Nonetheless, the reviewing court must
review the decision of the Board on the basis of the
Board’s findings, rather than on “post hoc rationalizations
for agency action.” In re Hounsfield, 699 F.2d 1320, 1324
(Fed. Cir. 1983) (quoting Burlington Truck Lines, Inc. v.
United States, 371 U.S. 156, 168 (1962)).
     We conclude, on the evidence and arguments pre-
sented, that the Board did not persuasively explain how a
person of ordinary skill in the art would conclude that
Biggers taught that the trajectory commands produced by
the neural network are to be input into a separate autopi-
lot function. The PTO’s shifting positions do not assist in
appellate review. See In re Thrift, 298 F.3d 1357, 1366
(Fed. Cir. 2002) (citing SEC v. Chenery Corp., 332 U.S.
194, 196 (1947)) (“a reviewing court, in dealing with a
determination or judgment which an administrative
IN RE VAIDYANATHAN                                         14

agency alone is authorized to make, must judge the
propriety of such action solely by the grounds invoked by
the agency”). However, we are not prepared to hold that
all three of the PTO’s conflicting interpretations of Big-
gers and other teachings with respect to autopilot func-
tionality are incorrect.       We remand for further
development of the record, and full reconsideration by the
agency.


                              B
    The applicant next argues that the Board erred as a
matter of law by failing to make any findings at all as to
some aspects of the obviousness analysis. He stresses
that the Board did not establish the level of ordinary skill
in the field of the invention, a necessary Graham factor.
He acknowledges that “the absence of specific findings on
the level of skill in the art does not give rise to reversible
error ‘where the prior art itself reflects an appropriate
level and a need for testimony is not shown,’” Okajima v.
Bourdeau, 261 F.3d 1350, 1355 (Fed. Cir. 2001) (quoting
Litton Industrial Prods., Inc. v. Solid State Systems Corp.,
775 F.2d 158, 163 (Fed Cir. 1985)), but he complains that
the Board made repeated reference to what a “person of
ordinary skill” would have understood or inferred, without
ever explaining that level of ordinary skill or citing evi-
dence to support these findings. As this court has ob-
served, “Skill in the art does not act as a bridge over gaps
in the substantive presentation of an obviousness case,
but instead supplies an important guarantee of objectivity
in the process.” Id.
    The PTO responds that the Board is not required to
make express findings as to the level of ordinary skill in
the field of the invention. The PTO states that reversal
on this basis is appropriate only when the Board’s failure
to make an express finding on this factor reasonably may
15                                      IN RE VAIDYANATHAN

have distorted the ultimate conclusion on obviousness.
See Custom Accessories, Inc. v. Jeffrey-Allan Industries,
Inc., 807 F.2d 955, 963 (Fed. Cir. 1986) (vacating obvious-
ness holding and remanding because the district court’s
failure to make specific findings on the level of ordinary
skill, along with failure to address other Graham factors,
suggested that the court had not properly applied the
Graham analysis). The PTO argues that the applicant
“has not attempted to show how the lack of an express
finding influenced the Board’s conclusion on obviousness,
or that the prior art in the record is inadequate to demon-
strate the appropriate level of skill.” PTO Brief at 28.
    The applicant replies that his argument is not simply
that the Board failed to make express findings as to the
level of skill; he states that the issue is uniquely relevant
because the examiner’s statements apparently reflect
personal experience in the field of the invention, but are
unaccompanied by explanation or reasoning. He states
that the Board, like the examiner, made conclusory state-
ments that it would have been obvious to a person of
ordinary skill to select and combine certain parts of
certain references; the Board’s analysis of this aspect
reads:
     To combine the feature of a neural network for de-
     termining the optimal trajectory as taught by
     Biggers with the missile guidance system of John-
     son to attain the advantages of each would have
     been obvious to a person of ordinary skill in the
     art, as this would involve nothing more than the
     predictable use of prior art elements according to
     their established functions.
Board Opinion at 10. The applicant argues that to sup-
port this conclusion it is necessary to explain how the
knowledge and competence of the ordinary skilled person
in this field would have led to this combination of previ-
ously uncombined elements.
IN RE VAIDYANATHAN                                         16

    We agree with the Solicitor that an explicit statement
of the level of ordinary skill is not always necessary in
evaluating the obviousness of a new technologic advance.
But whether or not stated explicitly, the perspective of a
person of ordinary skill must frame the obviousness
inquiry, and assertions of what such a person of ordinary
skill would have found to be obvious require sufficient
explanation to permit meaningful appellate review. In
this case, not only the Board but also the examiner an-
nounced their conclusions of obviousness without provid-
ing any evidentiary support or reasoning for why a person
of ordinary skill in the field of the invention would have
deemed it obvious to select and combine various steps
from different references, in the manner of the applicant.
This court explained in In re Zurko, 258 F.3d 1379 (Fed.
Cir. 2001), that the entry of the PTO into the deferential
review of the Administrative Procedure Act requires the
agency to provide support for its findings:
    With respect to core factual findings in a determi-
    nation of patentability, . . . the Board cannot sim-
    ply reach conclusions based on its own
    understanding or experience—or on its assess-
    ment of what would be basic knowledge or com-
    mon sense. Rather, the Board must point to some
    concrete evidence in the record in support of these
    findings. To hold otherwise would render the
    process of appellate review for substantial evi-
    dence on the record a meaningless exercise.
Id. at 1386.
    The PTO Solicitor argues that the Court in KSR held
that a combination of elements from different prior art
references is likely to be unpatentable if it would involve
nothing more than “the predictable use of prior art ele-
ments according to their established functions,” KSR, 550
U.S. at 417, and that the Board applied this reasoning to
the combination of Biggers and Johnson. KSR also clari-
17                                      IN RE VAIDYANATHAN

fied that recourse to “common sense,” viewed through the
perspective of a person of ordinary skill, is not barred in
the obviousness inquiry. As the applicant states, while
KSR relaxed some of the formalism of earlier decisions
requiring a “teaching, suggestion, or motivation” to com-
bine prior art references, it did not remove the need to
anchor the analysis in explanation of how a person of
ordinary skill would select and apply the teachings of the
references. See, e.g., id. at 417 (“If a person of ordinary
skill can implement a predictable variation, §103 likely
bars its patentability. For the same reason, if a technique
has been used to improve one device, and a person of
ordinary skill in the art would recognize that it would
improve similar devices in the same way, using the tech-
nique is obvious unless its actual application is beyond his
or her skill.”).
    The applicant complains that the Board simply rea-
soned from the hindsight knowledge of his successful
invention; he stresses that, unlike the facts in KSR, the
various steps that he combined were not known to be
combinable, and the result of increased precision in
missile guidance to the target was not previously known
or predictable.
    Obviousness is determined as a matter of foresight,
not hindsight. See id. at 421 (citing Graham, 383 U.S. at
36). KSR did not free the PTO’s examination process
from explaining its reasoning. In making an obviousness
rejection, the examiner should not rely on conclusory
statements that a particular feature of the invention
would have been obvious or was well known. Instead, the
examiner should elaborate, discussing the evidence or
reasoning that leads the examiner to such a conclusion.
Generally, the examiner cites prior art references to
demonstrate the state of knowledge. See 37 C.F.R.
§1.104(c)(2) (“In rejecting claims for want of novelty or
obviousness, the examiner must cite the best references at
IN RE VAIDYANATHAN                                        18

his or her command.”); Manual of Patent Examining
Procedure (MPEP) §706.02 (8th ed., rev. July 2008)
(“Prior art rejections should ordinarily be confined strictly
to the best available art. [citing exceptions] Such rejec-
tions should be backed up by the best other art rejections
available.”). If it is not possible for the examiner to pro-
vide this type of information, the examiner might choose
instead to provide an affidavit detailing the examiner’s
own personal knowledge (as a person approximating one
of ordinary skill in the art) of the technology in question.
See 37 C.F.R. §1.104(d)(2) (“When a rejection in an appli-
cation is based on facts within the personal knowledge of
an employee of the Office, the data shall be as specific as
possible, and the reference must be supported, when
called for by the applicant, by the affidavit of such em-
ployee, and such affidavit shall be subject to contradiction
or explanation by the affidavits of the applicant and other
persons.”). Where, as here, prior art references are cited
to support an obviousness rejection, the references them-
selves need not in every case provide a “specific hint or
suggestion” of the alteration needed to arrive at the
claimed invention; the examiner’s analysis “may include
recourse to logic, judgment, and common sense available
to a person of ordinary skill that do not necessarily re-
quire explication in any reference or expert opinion.”
Perfect Web Techs. v. InfoUSA, Inc., 587 F.3d 1324, 1329
(Fed. Cir. 2009). In these cases the examiner should at
least explain the logic or common sense that leads the
examiner to believe the claim would have been obvious.
Anything less than this results in a record that is insu-
lated from meaningful appellate review. Zurko, 258 F.3d
at 1386. If the examiner is able to render a claim obvious
simply by saying it is so, neither the Board nor this court
is capable of reviewing that determination. See KSR, 550
U.S. at 418, citing In re Kahn, 441 F.3d 977, 988 (Fed.
Cir. 2006) (“[R]ejections on obviousness grounds cannot be
sustained by mere conclusory statements; instead, there
19                                      IN RE VAIDYANATHAN

must be some articulated reasoning with some rational
underpinning to support the legal conclusion of obvious-
ness.”).
    Because there is insufficient elaboration of the exam-
iner’s or the Board’s reasoning in this record, we vacate
the Board’s rejection of claims 1–7. We remand for rede-
termination of the question of obviousness. On remand,
the PTO should determine obviousness based on evidence
of record or on the examiner’s detailed and articulated
reasoning. If there is neither record evidence nor detailed
examiner reasoning, the Board should not conclude that
Vaidyanathan’s claims are obvious.
                             II
     The Board addressed claims 8 and 9 separately, with
claim 9 agreed to be representative. Claim 9, in multiple
dependent form, may be rewritten in independent form as
follows:
     9. [A method of controlling a munition, vehicle or
     aircraft comprising the steps of:
     a) receiving information from sensors;
     b) processing the information with a neural net-
     work to obtain a desired trajectory for the muni-
     tion, vehicle or aircraft to follow;
     c) inputting the desired trajectory and the in-
     formation from internal sensor into an autopilot;
     and
     d) controlling the munition, vehicle or aircraft to
     fly the desired trajectory through the autopilot;
     wherein the information is received from external
     and internal sensors;
     wherein the external sensor information is infor-
     mation related to a target position;
IN RE VAIDYANATHAN                                         20

    wherein the neural network determines a desired
    trajectory for the munition, vehicle or aircraft;
    and]
    wherein the neural network is guiding the muni-
    tion, vehicle or aircraft to strike a target.


The Board found that “Biggers does not teach using the
neural network to guide the missile all the way to inter-
cept.” However, the Board concluded that the “to strike a
target” limitation does not adequately distinguish claim 9
from Biggers because it does not require that the neural
network guide the missile or munition all the way to
“intercept,” but instead merely requires that the neural
network guide the munition “to strike a target.” The
Board viewed the words “to strike a target” as a recitation
of intended purpose, rather than a step of a claimed
method. On this view, the Board held that because the
purpose in Biggers is also a target strike, Biggers teaches
this limitation and thus describes the same method as
claim 9. The Board stated: “In guiding the missile toward
the target to the optimum point in space where the mis-
sile guidance system can take control and guide the
missile 47 to intercept the target (FF1), the neural net-
work in the method taught by Biggers guides the missile
to strike a target.” Board Opinion at 11.
     The applicant argues that claim 9, when properly con-
strued in light of the specification, requires actual partici-
pation by the neural network until the point of intercept,
unlike the Biggers method. He argues that the Board
misconstrued the “to strike a target” limitation of claim 9,
and thereby misapplied Biggers. The applicant states
that the ’203 application describes for the first time the
use of a neural network in connection with the final stage
of flight leading to intercept, whereas Biggers describes
the use of a neural network only at an intermediate stage,
21                                      IN RE VAIDYANATHAN

to be replaced by a different terminal guidance system
before intercept.
    The PTO Solicitor responds that the broadest reason-
able claim interpretation that is supported by the specifi-
cation is adopted during examination, for the claims can
readily be amended during examination, to impart preci-
sion if needed. We agree with this protocol as an exami-
nation expedient, for its purpose is to aid in sharpening
the claims in order to avoid ambiguity or uncertainty in
the issued patent. See e.g., In re Skvorecz, 580 F.3d 1262,
1267 (Fed. Cir. 2009); In re Buszard, 504 F.3d 1364,
1366–67 (Fed. Cir. 2007); In re Prater, 415 F.2d 1393,
1396 (CCPA 1969). However, the PTO’s “broadest” inter-
pretation must be reasonable, and must be in conformity
with the invention as described in the specification.
    The Board’s interpretation of claim 9 finds no support
in the ’203 specification, and is not a reasonable interpre-
tation under the rules of claim construction. The descrip-
tion in the specification consistently indicates that the
neural network guides the munition all the way intercept.
The ’203 specification uses the word “strike” synony-
mously with “intercept,” foreclosing the divergent mean-
ings the Board seeks to attach to these terms. The
Board’s rejection of claims 8 and 9 was based on an incor-
rect interpretation of these claims. That rejection is
vacated and remanded for reconsideration under the
correct interpretation of the claims, and in further view of
the issues with respect to obviousness as discussed in
connection with claims 1–7.
                            III
    Both sides have raised additional arguments, for ex-
ample with respect to the impact of the Johnson reference
on the “sensor” aspect of step 1(c). In view of our remand
for further prosecution of claims 1–9, we need not reach
the additional issues, for none appears to be dispositive of
IN RE VAIDYANATHAN                                     22

either allowance or rejection. 2 They may be considered on
remand if relevant to the issues.


            VACATED AND REMANDED


DYK, Circuit Judge, concurs in the judgment.




   2    In its Statement of Facts, the PTO points out that
the appealed claims do not limit the ’203 application’s
invention to a specific use of a neural network based on
the specific reflex response that is the primary matter
described in the specification, and thus suggests that the
appealed claims are too broadly drawn to distinguish the
invention from the combination of Biggers and Johnson.
This aspect may warrant attention on remand.
